Method for ue transmitting sidelink signal in wireless communication system supporting sidelink, and device therefor

ABSTRACT

Disclosed, according to various embodiments, are a method for a UE transmitting a sidelink signal in a wireless communication system supporting a sidelink, and a device therefor. Disclosed is a method for transmitting a sidelink signal and a device therefor, the method comprising the steps of: measuring state information including mobility information; receiving a first sidelink signal including control information; and determining whether to transmit a second sidelink signal, wherein, on the basis of the control information, including information on a cluster area, and the state information, including information on a location included in the cluster area, a UE monitors the receiving or not of a third sidelink signal transmitted by other UEs during a predetermined duration, and whether to transmit the second sidelink signal is determined on the basis of the result of the monitoring.

TECHNICAL FIELD

The present disclosure relates to a method for enabling a user equipment (UE) to transmit a sidelink signal in a wireless communication system and a device for the same, and more particularly to a method for enabling a user equipment (UE) to determine whether to transmit a sidelink signal in response to a sidelink signal received from another UE, and a device for the same.

BACKGROUND ART

Wireless communication systems have been widely deployed to provide various types of communication services such as voice or data. In general, a wireless communication system is a multiple access system that supports communication of multiple users by sharing available system resources (a bandwidth, transmission power, etc.). Examples of multiple access systems include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency division multiple access (SC-FDMA) system, and a multi carrier frequency division multiple access (MC-FDMA) system.

A sidelink (SL) refers to a communication method in which a direct link is established between user equipment (UE), and voice or data is directly exchanged between terminals without going through a base station (BS). SL is being considered as one way to solve the burden of the base station due to the rapidly increasing data traffic.

V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, and infrastructure-built objects through wired/wireless communication. V2X may be divided into four types: vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). V2X communication may be provided through a PC5 interface and/or a Uu interface.

As more and more communication devices require larger communication capacities in transmitting and receiving signals, there is a need for mobile broadband communication improved from the legacy radio access technology. Accordingly, communication systems considering services/UEs sensitive to reliability and latency are under discussion. A next-generation radio access technology in consideration of enhanced mobile broadband communication, massive Machine Type Communication (MTC), and Ultra-Reliable and Low Latency Communication (URLLC) may be referred to as new radio access technology (RAT) or new radio (NR). Even in NR, vehicle-to-everything (V2X) communication may be supported.

FIG. 1 is a diagram comparing RAT-based V2X communication before NR with NR-based V2X communication.

Regarding V2X communication, in RAT prior to NR, a scheme for providing a safety service based on V2X messages such as a basic safety message (BSM), a cooperative awareness message (CAM), and a decentralized environmental notification message (DENM) was mainly discussed. The V2X message may include location information, dynamic information, and attribute information. For example, the UE may transmit a periodic message type CAM and/or an event triggered message type DENM to another UE.

For example, the CAM may include dynamic state information about a vehicle such as direction and speed, vehicle static data such as dimensions, and basic vehicle information such as external lighting conditions and route details. For example, a UE may broadcast the CAM, and the CAM latency may be less than 100 ms. For example, when an unexpected situation such as a breakdown of the vehicle or an accident occurs, the UE may generate a DENM and transmit the same to another UE. For example, all vehicles within the transmission coverage of the UE may receive the CAM and/or DENM. In this case, the DENM may have a higher priority than the CAM.

Regarding V2X communication, various V2X scenarios have been subsequently introduced in NR. For example, the various V2X scenarios may include vehicle platooning, advanced driving, extended sensors, and remote driving.

For example, based on vehicle platooning, vehicles may dynamically form a group and move together. For example, to perform platoon operations based on vehicle platooning, vehicles belonging to the group may receive periodic data from a leading vehicle. For example, the vehicles belonging to the group may reduce or increase the distance between the vehicles based on the periodic data.

For example, based on advanced driving, a vehicle may be semi-automated or fully automated. For example, each vehicle may adjust trajectories or maneuvers based on data acquired from local sensors of nearby vehicles and/or nearby logical entities. Also, for example, each vehicle may share driving intention with nearby vehicles.

For example, on the basis of extended sensors, raw data or processed data acquired through local sensors, or live video data may be exchanged between a vehicle, a logical entity, UEs of pedestrians and/or a V2X application server. Thus, for example, the vehicle may recognize an environment that is improved over an environment that may be detected using its own sensor.

For example, for a person who cannot drive or a remote vehicle located in a dangerous environment, a remote driver or V2X application may operate or control the remote vehicle based on remote driving. For example, when a route is predictable as in the case of public transportation, cloud computing-based driving may be used to operate or control the remote vehicle. For example, access to a cloud-based back-end service platform may be considered for remote driving.

A method to specify service requirements for various V2X scenarios such as vehicle platooning, advanced driving, extended sensors, and remote driving is being discussed in the NR-based V2X communication field.

DISCLOSURE Technical Problem

An object of the present disclosure is to provide a method and device for minimizing the amount of communication traffic increasing by safety messages of UEs by determining whether to transmit a sidelink or safety message based on clustering in a situation where the UEs are close to each other, thereby minimizing power consumption of the UEs.

It will be appreciated by persons skilled in the art that the objects that could be achieved with the present disclosure are not limited to what has been particularly described hereinabove and the above and other objects that the present disclosure could achieve will be more clearly understood from the following detailed description.

Technical Solutions

In accordance with an aspect of the present disclosure, a method for enabling a user equipment (UE) to transmit a sidelink signal in a wireless communication system supporting sidelink may include measuring status information including mobility information; receiving a first sidelink signal including control information; and determining whether to transmit a second sidelink signal. The UE may monitor whether a third sidelink signal from each of other UEs is received during a predetermined period based on the control information having information about a cluster area and the status information having location information belonging to the cluster area. Transmission or non-transmission of the second sidelink signal may be determined based on the result of monitoring.

The second sidelink signal may be transmitted when the third sidelink signal is not received during the predetermined period.

In a situation where the third sidelink signal is received during the predetermined period, when information about a geographical area corresponding to the cluster area is included in the third sidelink signal, transmission of the second sidelink signal is not allowed.

The method may further include receiving at least one of a personal safety message (PSM), a cooperative awareness message (CAM), a decentralized environmental notification message (DENM), and a threat notification message (TNM); and calculating a collision risk (CR) value based on the received at least one message and the status information.

In a situation where the third sidelink signal is received during the predetermined period, when the calculated collision risk (CR) value is equal to or higher than a collision risk (CR) value obtained from the third sidelink signal, the second sidelink signal may be transmitted.

In a situation where information about a collision risk (CR) value is additionally included in the control information, when the calculated collision risk (CR) value is equal to or higher than the collision risk (CR) reference value, the second sidelink signal may be transmitted regardless of reception or non-reception of the third sidelink signal.

In a situation where the third sidelink signal is received during the predetermined period, when a collision area and a collision time estimated based on the status information and the at least one message are matched to a collision area and a collision time included in the third sidelink signal, transmission of the second sidelink signal is not allowed.

In a situation where identifier (ID) information for each cluster area is additionally included in the control information, when ID information for the cluster area corresponding to location information included in the status information is identical to an identifier (ID) of the user equipment (UE), the second sidelink signal may be transmitted regardless of reception or non-reception of the third sidelink signal.

The control information may further include instruction information indicating any one of schemes for transmitting a plurality of clustering-based sidelink signals, so that the schemes may determine whether to transmit the second sidelink signal based on at least one of a collision risk (CR) value, a geographical area, a collision area, and a collision time.

The second sidelink signal may include at least one of a collision risk (CR) value, a geographical area, a collision area, and a collision time, based on the instruction information.

The second sidelink signal may include a personal safety message (PSM) including collision avoidance guide information that requests change of a movement angle and a movement speed.

The personal safety message (PSM) may further include information about a collision area and a collision time that are estimated by the user equipment (UE).

The sidelink signal may be a cooperative awareness message (CAM).

In accordance with another aspect of the present disclosure, a user equipment (UE) configured to transmit a safety message in a wireless communication system supporting sidelink may include a radio frequency (RF) transceiver; and a processor connected to the RF transceiver. The processor may measure status information including mobility information, may receive a first sidelink signal including control information, may monitor whether a third sidelink signal from each of other UEs is received during a predetermined period based on the control information having information about a cluster area and the status information having location information belonging to the cluster area, and may determine whether to transmit the second sidelink signal based on the result of monitoring.

In accordance with another aspect of the present disclosure, a chip set configured to transmit a safety message in a wireless communication system supporting sidelink may include at least one processor; and at least one memory operatively connected to the at least one processor, and configured to store instructions such that the at least one processor performs specific operations by executing the instructions. The specific operations may include measuring status information including mobility information; receiving a first sidelink signal including control information; monitoring whether a third sidelink signal from each of other UEs is received during a predetermined period based on the control information having information about a cluster area and the status information having location information belonging to the cluster area; and determining whether to transmit the second sidelink signal based on the result of monitoring.

The processor may control a driving mode of a device connected to the chip set, based on the cluster area.

Advantageous Effects

As is apparent from the above description, the embodiments of the present disclosure can minimize the amount of communication traffic increasing by safety messages of UEs by determining whether to transmit a sidelink or safety message based on clustering in a situation where the UEs are close to each other, thereby minimizing power consumption of the UEs.

It will be appreciated by persons skilled in the art that that the effects that can be achieved through the embodiments of the present disclosure are not limited to those described above and other advantageous effects of the present disclosure will be more clearly understood from the following detailed description.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure.

FIG. 1 is a diagram for explaining by comparing V2X communication based on RAT before NR and V2X communication based on NR.

FIG. 2 illustrates the structure of an LTE system to which embodiment(s) are applicable.

FIG. 3 illustrates a user-plane radio protocol architecture to which embodiment(s) are applicable.

FIG. 4 illustrates a control-plane radio protocol architecture to which embodiment(s) are applicable.

FIG. 5 illustrates the structure of an NR system to which embodiment(s) are applicable.

FIG. 6 illustrates functional split between an NG-RAN and a 5GC to which embodiment(s) are applicable.

FIG. 7 illustrates the structure of an NR radio frame to which embodiment(s) are applicable.

FIG. 8 illustrates the slot structure of an NR frame to which embodiment(s) are applicable.

FIG. 9 illustrates a radio protocol architecture for SL communication.

FIG. 10 shows the structures of an S-SSB according to CP types.

FIG. 11 illustrates UEs performing V2X or SL communication.

FIG. 12 illustrates resource units for V2X or SL communication.

FIG. 13 illustrates a procedure in which UEs perform V2X or SL communication according to a transmission mode.

FIG. 14 illustrates a V2X synchronization source or synchronization reference to which embodiments(s) are applicable.

FIG. 15 is a schematic diagram illustrating an intelligent transport system (ITS) station reference architecture.

FIGS. 16 and 17 are conceptual diagrams illustrating methods for transmitting a safety message including collision avoidance guide information

FIG. 18 is a flowchart illustrating a method for transmitting a safety message including collision avoidance guide information.

FIG. 19 is a conceptual diagram illustrating a method for enabling a vulnerable road user (VRU) to determine whether to transmit a safety message based on a clustering scheme.

FIG. 20 is a flowchart illustrating a method for enabling the VRU to determine whether to transmit a safety message according to a clustering-based safety message transmission scheme.

FIGS. 21 and 22 are conceptual diagrams illustrating a method for enabling the VRU to determine whether to transmit a safety message based on a clustering related signal transmitted by a vehicle or a road side unit (RSU).

FIGS. 23 and 24 are conceptual diagrams illustrating a method for enabling the VRU to determine whether to transmit a safety message according to a collision risk—based clustering scheme.

FIG. 25 illustrates a communication system applied to the present disclosure;

FIG. 26 illustrates wireless devices applicable to the present disclosure.

FIG. 27 illustrates another example of a wireless device to which the present disclosure is applied. The wireless device may be implemented in various forms according to use-examples/services.

FIG. 28 illustrates a hand-held device applied to the present disclosure;

FIG. 29 illustrates a vehicle or an autonomous driving vehicle applied to the present disclosure.

BEST MODE

The wireless communication system is a multiple access system that supports communication with multiple users by sharing available system resources (eg, bandwidth, transmission power, etc.). Examples of the multiple access system include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency (SC-FDMA) system, a multi carrier frequency division multiple access (MC-FDMA) system, and the like.

A sidelink refers to a communication scheme in which a direct link is established between user equipments (UEs) to directly exchange voice or data between UEs without assistance from a base station (BS). The sidelink is being considered as one way to address the burden on the BS caused by rapidly increasing data traffic.

Vehicle-to-everything (V2X) refers to a communication technology for exchanging information with other vehicles, pedestrians, and infrastructure-built objects through wired/wireless communication. V2X may be divided into four types: vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). V2X communication may be provided through a PC5 interface and/or a Uu interface.

As more and more communication devices require larger communication capacities in transmitting and receiving signals, there is a need for mobile broadband communication improved from the legacy radio access technology. Accordingly, communication systems considering services/UEs sensitive to reliability and latency are under discussion. A next-generation radio access technology in consideration of enhanced mobile broadband communication, massive MTC, and Ultra-Reliable and Low Latency Communication (URLLC) may be referred to as new radio access technology (RAT) or new radio (NR). Even in NR, V2X communication may be supported.

Techniques described herein may be used in various wireless access systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier-frequency division multiple access (SC-FDMA), etc. CDMA may be implemented as a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented as a radio technology such as global system for mobile communications (GSM)/general packet radio service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented as a radio technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, evolved-UTRA (E-UTRA) etc. UTRA is a part of universal mobile telecommunications system (UMTS). 3GPP LTE is a part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA for downlink and SC-FDMA for uplink. LTE-A is an evolution of 3GPP LTE. 3GPP NR (New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE/LTE-A/LTE-A pro.

5G NR is a successor technology of LTE-A, and is a new clean-slate mobile communication system with characteristics such as high performance, low latency, and high availability. 5G NR may utilize all available spectrum resources, from low frequency bands below 1 GHz to intermediate frequency bands from 1 GHz to 10 GHz and high frequency (millimeter wave) bands above 24 GHz.

For clarity of explanation, LTE-A or 5G NR is mainly described, but the technical spirit of the embodiment(s) is not limited thereto

FIG. 2 illustrates the structure of an LTE system to which the present disclosure is applicable. This may also be called an evolved UMTS terrestrial radio access network (E-UTRAN) or LTE/LTE-A system.

Referring to FIG. 2, the E-UTRAN includes evolved Node Bs (eNBs) 20 which provide a control plane and a user plane to UEs 10. A UE 10 may be fixed or mobile, and may also be referred to as a mobile station (MS), user terminal (UT), subscriber station (SS), mobile terminal (MT), or wireless device. An eNB 20 is a fixed station communication with the UE 10 and may also be referred to as a base station (BS), a base transceiver system (BTS), or an access point.

eNBs 20 may be connected to each other via an X2 interface. An eNB 20 is connected to an evolved packet core (EPC) 39 via an Si interface. More specifically, the eNB 20 is connected to a mobility management entity (MME) via an S1-MME interface and to a serving gateway (S-GW) via an S1-U interface.

The EPC 30 includes an MME, an S-GW, and a packet data network-gateway (P-GW). The MME has access information or capability information about UEs, which are mainly used for mobility management of the UEs. The S-GW is a gateway having the E-UTRAN as an end point, and the P-GW is a gateway having a packet data network (PDN) as an end point.

Based on the lowest three layers of the open system interconnection (OSI) reference model known in communication systems, the radio protocol stack between a UE and a network may be divided into Layer 1 (L1), Layer 2 (L2) and Layer 3 (L3). These layers are defined in pairs between a UE and an Evolved UTRAN (E-UTRAN), for data transmission via the Uu interface. The physical (PHY) layer at L1 provides an information transfer service on physical channels. The radio resource control (RRC) layer at L3 functions to control radio resources between the UE and the network. For this purpose, the RRC layer exchanges RRC messages between the UE and an eNB.

FIG. 3 illustrates a user-plane radio protocol architecture to which the present disclosure is applicable.

FIG. 4 illustrates a control-plane radio protocol architecture to which the present disclosure is applicable. A user plane is a protocol stack for user data transmission, and a control plane is a protocol stack for control signal transmission.

Referring to FIGS. 3 and 4, the PHY layer provides an information transfer service to its higher layer on physical channels. The PHY layer is connected to the medium access control (MAC) layer through transport channels and data is transferred between the MAC layer and the PHY layer on the transport channels. The transport channels are divided according to features with which data is transmitted via a radio interface.

Data is transmitted on physical channels between different PHY layers, that is, the PHY layers of a transmitter and a receiver. The physical channels may be modulated in orthogonal frequency division multiplexing (OFDM) and use time and frequencies as radio resources.

The MAC layer provides services to a higher layer, radio link control (RLC) on logical channels. The MAC layer provides a function of mapping from a plurality of logical channels to a plurality of transport channels. Further, the MAC layer provides a logical channel multiplexing function by mapping a plurality of logical channels to a single transport channel A MAC sublayer provides a data transmission service on the logical channels.

The RLC layer performs concatenation, segmentation, and reassembly for RLC serving data units (SDUs). In order to guarantee various quality of service (QoS) requirements of each radio bearer (RB), the RLC layer provides three operation modes, transparent mode (TM), unacknowledged mode (UM), and acknowledged Mode (AM). An AM RLC provides error correction through automatic repeat request (ARQ).

The RRC layer is defined only in the control plane and controls logical channels, transport channels, and physical channels in relation to configuration, reconfiguration, and release of RBs. An RB refers to a logical path provided by L1 (the PHY layer) and L2 (the MAC layer, the RLC layer, and the packet data convergence protocol (PDCP) layer), for data transmission between the UE and the network.

The user-plane functions of the PDCP layer include user data transmission, header compression, and ciphering. The control-plane functions of the PDCP layer include control-plane data transmission and ciphering/integrity protection.

RB establishment amounts to a process of defining radio protocol layers and channel features and configuring specific parameters and operation methods in order to provide a specific service. RBs may be classified into two types, signaling radio bearer (SRB) and data radio bearer (DRB). The SRB is used as a path in which an RRC message is transmitted on the control plane, whereas the DRB is used as a path in which user data is transmitted on the user plane.

Once an RRC connection is established between the RRC layer of the UE and the RRC layer of the E-UTRAN, the UE is placed in RRC_CONNECTED state, and otherwise, the UE is placed in RRC_IDLE state. In NR, RRC_INACTIVE state is additionally defined. A UE in the RRC_INACTIVE state may maintain a connection to a core network, while releasing a connection from an eNB.

DL transport channels carrying data from the network to the UE include a broadcast channel (BCH) on which system information is transmitted and a DL shared channel (DL SCH) on which user traffic or a control message is transmitted. Traffic or a control message of a DL multicast or broadcast service may be transmitted on the DL-SCH or a DL multicast channel (DL MCH). UL transport channels carrying data from the UE to the network include a random access channel (RACH) on which an initial control message is transmitted and an UL shared channel (UL SCH) on which user traffic or a control message is transmitted.

The logical channels which are above and mapped to the transport channels include a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and a multicast traffic channel (MTCH).

A physical channel includes a plurality of OFDM symbols in the time domain by a plurality of subcarriers in the frequency domain. One subframe includes a plurality of OFDM symbols in the time domain. An RB is a resource allocation unit defined by a plurality of OFDM symbols by a plurality of subcarriers. Further, each subframe may use specific subcarriers of specific OFDM symbols (e.g., the first OFDM symbol) in a corresponding subframe for a physical DL control channel (PDCCH), that is, an L1/L2 control channel A transmission time interval (TTI) is a unit time for subframe transmission.

FIG. 5 illustrates the structure of a NR system to which the present disclosure is applicable.

Referring to FIG. 5, a next generation radio access network (NG-RAN) may include a next generation Node B (gNB) and/or an eNB, which provides user-plane and control-plane protocol termination to a UE. In FIG. 5, the NG-RAN is shown as including only gNBs, by way of example. A gNB and an eNB are connected to each other via an Xn interface. The gNB and the eNB are connected to a 5G core network (5GC) via an NG interface. More specifically, the gNB and the eNB are connected to an access and mobility management function (AMF) via an NG-C interface and to a user plane function (UPF) via an NG-U interface.

FIG. 6 illustrates functional split between the NG-RAN and the 5GC to which the present disclosure is applicable.

Referring to FIG. 6, a gNB may provide functions including inter-cell radio resource management (RRM), radio admission control, measurement configuration and provision, and dynamic resource allocation. The AMF may provide functions such as non-access stratum (NAS) security and idle-state mobility processing. The UPF may provide functions including mobility anchoring and protocol data unit (PDU) processing. A session management function (SMF) may provide functions including UE Internet protocol (IP) address allocation and PDU session control.

FIG. 7 illustrates the structure of a NR radio frame to which the present disclosure is applicable.

Referring to FIG. 7, a radio frame may be used for UL transmission and DL transmission in NR. A radio frame is 10 ms in length, and may be defined by two 5-ms half-frames. An HF may include five 1-ms subframes. A subframe may be divided into one or more slots, and the number of slots in an SF may be determined according to a subcarrier spacing (SCS). Each slot may include 12 or 14 OFDM(A) symbols according to a cyclic prefix (CP).

In a normal CP (NCP) case, each slot may include 14 symbols, whereas in an extended CP (ECP) case, each slot may include 12 symbols. Herein, a symbol may be an OFDM symbol (or CP-OFDM symbol) or an SC-FDMA symbol (or DFT-s-OFDM symbol).

Table 1 below lists the number of symbols per slot Nslotsymb, the number of slots per frame Nframe,uslot, and the number of slots per subframe Nsubframe,uslot according to an SCS configuration μ in the NCP case.

TABLE 1 SCS (15*2u) N^(slot) _(symb) N^(frame, u) _(slot) N^(subframe, u) _(slot)  15 KHz (u = 0) 14 10 1  30 KHz (u = 1) 14 20 2  60 KHz (u = 2) 14 40 4 120 KHz (u = 3) 14 80 8 240 KHz (u = 4) 14 160 16

Table 2 below lists the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to an SCS in the ECP case.

TABLE 2 SCS (15*2{circumflex over ( )}u) N^(slot) _(symb) N^(frame, u) _(slot) N^(subframe, u) _(slot) 60 KHz (u = 2) 12 40 4

In the NR system, different OFDM(A) numerologies (e.g., SCSs, CP lengths, etc.) may be configured for a plurality of cells aggregated for one UE. Thus, the (absolute) duration of a time resource (e.g., SF, slot, or TTI) including the same number of symbols may differ between the aggregated cells (such a time resource is commonly referred to as a time unit (TU) for convenience of description).

In NR, multiple numerologies or SCSs to support various 5G services may be supported. For example, a wide area in conventional cellular bands may be supported when the SCS is 15 kHz, and a dense urban environment, lower latency, and a wider carrier bandwidth may be supported when the SCS is 30 kHz/60 kHz. When the SCS is 60 kHz or higher, a bandwidth wider than 24.25 GHz may be supported to overcome phase noise.

The NR frequency band may be defined as two types of frequency ranges. The two types of frequency ranges may be FR1 and FR2. The numerical values of the frequency ranges may be changed. For example, the two types of frequency ranges may be configured as shown in Table 3 below. Among the frequency ranges used in the NR system, FR1 may represent “sub 6 GHz range” and FR2 may represent “above 6 GHz range” and may be called millimeter wave (mmW).

TABLE 3 Frequency Range Subcarrier Spacing designation Corresponding frequency range (SCS) FR1  450 MHz-6000 MHz 15, 30, 60 KHz FR2 24250 MHz-52600 MHz 60, 120, 240 KHz

As mentioned above, the numerical values of the frequency ranges of the NR system may be changed. For example, FR1 may include a band of 410 MHz to 7125 MHz as shown in Table 4 below. That is, FR1 may include a frequency band of 6 GHz (or 5850 MHz, 5900 MHz, 5925 MHz, etc.) or higher. For example, the frequency band of 6 GHz (or 5850 MHz, 5900 MHz, 5925 MHz, etc.) or higher included in FR1 may include an unlicensed band. The unlicensed band may be used for various purposes, for example, for communication for vehicles (e.g., autonomous driving).

TABLE 4 Frequency Range Subcarrier Spacing designation Corresponding frequency range (SCS) FR1  410 MHz-7125 MHz 15, 30, 60 KHz FR2 24250 MHz-52600 MHz 60, 120, 240 KHz

FIG. 8 illustrates the slot structure of a NR frame to which the present disclosure is applicable.

Referring to FIG. 8, one slot includes a plurality of symbols in the time domain. For example, one slot may include 14 symbols in a normal CP and 12 symbols in an extended CP. Alternatively, one slot may include 7 symbols in the normal CP and 6 symbols in the extended CP.

A carrier may include a plurality of subcarriers in the frequency domain. A resource block (RB) is defined as a plurality of consecutive subcarriers (e.g., 12 subcarriers) in the frequency domain. A bandwidth part (BWP) may be defined as a plurality of consecutive (P)RBs in the frequency domain, and the BWP may correspond to one numerology (e.g., SCS, CP length, etc.). The carrier may include up to N (e.g., 5) BWPs. Data communication may be conducted in an activated BWP. In a resource grid, each element may be referred to as a resource element (RE) and may be mapped to one complex symbol.

The wireless interface between UEs or the wireless interface between a UE and a network may be composed of an L1 layer, an L2 layer, and an L3 layer. In various embodiments of the present disclosure, the L1 layer may represent a physical layer. The L2 layer may represent, for example, at least one of a MAC layer, an RLC layer, a PDCP layer, and an SDAP layer. The L3 layer may represent, for example, an RRC layer.

Hereinafter, V2X or sidelink (SL) communication will be described.

FIG. 9 illustrates a radio protocol architecture for SL communication. Specifically, FIG. 9-(a) shows a user plane protocol stack of NR, and FIG. 9-(b) shows a control plane protocol stack of NR.

Hereinafter, a sidelink synchronization signal (SLSS) and synchronization information will be described.

The SLSS is an SL-specific sequence, and may include a primary sidelink synchronization signal (PSSS) and a secondary sidelink synchronization signal (SSSS). The PSSS may be referred to as a sidelink primary synchronization signal (S-PSS), and the SSSS may be referred to as a sidelink secondary synchronization signal (S-SSS). For example, length-127 M-sequences may be used for the S-PSS, and length-127 gold sequences may be used for the S-SSS. For example, the UE may detect an initial signal and acquire synchronization using the S-PSS. For example, the UE may acquire detailed synchronization using the S-PSS and the S-SSS, and may detect a synchronization signal ID.

A physical sidelink broadcast channel (PSBCH) may be a (broadcast) channel on which basic (system) information that the UE needs to know first before transmission and reception of an SL signal is transmitted. For example, the basic information may include SLSS related information, a duplex mode (DM), time division duplex uplink/downlink (TDD UL/DL) configuration, resource pool related information, the type of an application related to the SLSS, a subframe offset, and broadcast information. For example, for evaluation of PSBCH performance, the payload size of PSBCH in NR V2X may be 56 bits including CRC of 24 bits.

The S-PSS, S-SSS, and PSBCH may be included in a block format (e.g., an SL synchronization signal (SS)/PSBCH block, hereinafter sidelink-synchronization signal block (S-SSB)) supporting periodic transmission. The S-SSB may have the same numerology (i.e., SCS and CP length) as a physical sidelink control channel (PSCCH)/physical sidelink shared channel (PSSCH) in the carrier, and the transmission bandwidth thereof may be within a (pre)set sidelink BWP (SL BWP). For example, the bandwidth of the S-SSB may be 11 resource blocks (RBs). For example, the PSBCH may span 11 RBs. The frequency position of the S-SSB may be (pre)set. Accordingly, the UE does not need to perform hypothesis detection at a frequency to discover the S-SSB in the carrier.

In the NR SL system, a plurality of numerologies having different SCSs and/or CP lengths may be supported. In this case, as the SCS increases, the length of the time resource in which the transmitting UE transmits the S-SSB may be shortened. Thereby, the coverage of the S-SSB may be narrowed. Accordingly, in order to guarantee the coverage of the S-SSB, the transmitting UE may transmit one or more S-SSBs to the receiving UE within one S-SSB transmission period according to the SCS. For example, the number of S-SSBs that the transmitting UE transmits to the receiving UE within one S-SSB transmission period may be pre-configured or configured for the transmitting UE. For example, the S-SSB transmission period may be 160 ms. For example, for all SCSs, the S-SSB transmission period of 160 ms may be supported.

For example, when the SCS is 15 kHz in FR1, the transmitting UE may transmit one or two S-SSBs to the receiving UE within one S-SSB transmission period. For example, when the SCS is 30 kHz in FR1, the transmitting UE may transmit one or two S-SSBs to the receiving UE within one S-SSB transmission period. For example, when the SCS is 60 kHz in FR1, the transmitting UE may transmit one, two, or four S-SSBs to the receiving UE within one S-SSB transmission period.

For example, when the SCS is 60 kHz in FR2, the transmitting UE may transmit 1, 2, 4, 8, 16 or 32 S-SSBs to the receiving UE within one S-SSB transmission period. For example, when SCS is 120 kHz in FR2, the transmitting UE may transmit 1, 2, 4, 8, 16, 32 or 64 S-SSBs to the receiving UE within one S-SSB transmission period.

When the SCS is 60 kHz, two types of CPs may be supported. In addition, the structure of the S-SSB transmitted from the transmitting UE to the receiving UE may depend on the CP type. For example, the CP type may be normal CP (NCP) or extended CP (ECP). Specifically, for example, when the CP type is NCP, the number of symbols to which the PSBCH is mapped in the S-SSB transmitted by the transmitting UE may be 9 or 8. On the other hand, for example, when the CP type is ECP, the number of symbols to which the PSBCH is mapped in the S-SSB transmitted by the transmitting UE may be 7 or 6. For example, the PSBCH may be mapped to the first symbol in the S-SSB transmitted by the transmitting UE. For example, upon receiving the S-SSB, the receiving UE may perform an automatic gain control (AGC) operation in the period of the first symbol for the S-SSB.

FIG. 10 illustrates the structures of an S-SSB according to CP types. FIG. 10-(a) shows the structure of the S-SSB when the CP type is NCP.

For example, the structure of the S-SSB, that is, the order of symbols to which the S-PSS, S-SSS, and PSBCH are mapped in the S-SSB transmitted by the transmitting UE when the CP type is NCP may be shown in FIG. 20.

FIG. 10-(b) shows the structure of the S-SSB when the CP type is ECP.

For example, when the CP type is ECP, the number of symbols to which the transmitting UE maps the PSBCH after the S-SSS in the S-SSB may be 6, unlike in FIG. 20. Accordingly, the coverage of the S-SSB may differ between the CP types, NCP and ECP.

Each SLSS may have an SL synchronization identifier (SLSS ID).

For example, in the case of LTE SL or LTE V2X, the value of the SLSS ID may be defined based on a combination of two different S-PSS sequences and 168 different S-SSS sequences. For example, the number of SLSS IDs may be 336. For example, the value of the SLSS ID may be any one of 0 to 335.

For example, in the case of NR SL or NR V2X, the value of the SLSS ID may be defined based on a combination of two different S-PSS sequences and 336 different S-SSS sequences. For example, the number of SLSS IDs may be 672. For example, the value of the SLSS ID may be any one of 0 to 671. For example, one S-PSS of the two different S-PSSs may be associated with in-coverage, and the other S-PSS may be associated with out-of-coverage. For example, SLSS IDs of 0 to 335 may be used in in-coverage, and SLSS IDs of 336 to 671 may be used in out-of-coverage.

In order to improve the S-SSB reception performance of the receiving UE, the transmitting UE needs to optimize the transmit power according to the characteristics of respective signals constituting the S-SSB. For example, according to the peak to average power ratio (PAPR) of each signal constituting the S-SSB, the transmitting UE may determine the value of maximum power reduction (MPR) for each signal. For example, when the PAPR differs between the S-PSS and the S-SSS which constitute the S-SSB, the transmitting UE may apply an optimal MPR value to transmission of each of the S-PSS and the S-SSS in order to improve the S-SSB reception performance of the receiving UE. Also, for example, in order for the transmitting UE to perform an amplification operation on each signal, a transition period may be applied. The transition period may reserve a time required for the transmitter amplifier of the transmitting UE to perform a normal operation at the boundary where the transmit power of the transmitting UE varies. For example, in the case of FR1, the transition period may be 10 μs. For example, in the case of FR2, the transition period may be 5 μs. For example, a search window in which the receiving UE is to detect the S-PSS may be 80 ms and/or 160 ms.

FIG. 11 illustrates UEs performing V2X or SL communication.

Referring to FIG. 11, in V2X or SL communication, the term UE may mainly refer to a user's UE. However, when network equipment such as a BS transmits and receives signals according to a communication scheme between UEs, the BS may also be regarded as a kind of UE. For example, UE 1 may be the first device 100, and UE 2 may be the second device 200.

For example, UE 1 may select a resource unit corresponding to a specific resource in a resource pool, which represents a set of resources. Then, UE 1 may transmit an SL signal through the resource unit. For example, UE 2, which is a receiving UE, may receive a configuration of a resource pool in which UE 1 may transmit a signal, and may detect a signal of UE 1 in the resource pool.

Here, when UE 1 is within the connection range of the BS, the BS may inform UE 1 of a resource pool. On the other hand, when the UE 1 is outside the connection range of the BS, another UE may inform UE 1 of the resource pool, or UE 1 may use a preconfigured resource pool.

In general, the resource pool may be composed of a plurality of resource units, and each UE may select one or multiple resource units and transmit an SL signal through the selected units.

FIG. 12 illustrates resource units for V2X or SL communication.

Referring to FIG. 12, the frequency resources of a resource pool may be divided into NF sets, and the time resources of the resource pool may be divided into NT sets. Accordingly, a total of NF*NT resource units may be defined in the resource pool. FIG. 12 shows an exemplary case where the resource pool is repeated with a periodicity of NT subframes.

As shown in FIG. 12, one resource unit (e.g., Unit #0) may appear periodically and repeatedly. Alternatively, in order to obtain a diversity effect in the time or frequency dimension, an index of a physical resource unit to which one logical resource unit is mapped may change in a predetermined pattern over time. In this structure of resource units, the resource pool may represent a set of resource units available to a UE which intends to transmit an SL signal.

Resource pools may be subdivided into several types. For example, according to the content in the SL signal transmitted in each resource pool, the resource pools may be divided as follows.

(1) Scheduling assignment (SA) may be a signal including information such as a position of a resource through which a transmitting UE transmits an SL data channel, a modulation and coding scheme (MCS) or multiple input multiple output (MIMO) transmission scheme required for demodulation of other data channels, and timing advance (TA). The SA may be multiplexed with SL data and transmitted through the same resource unit. In this case, an SA resource pool may represent a resource pool in which SA is multiplexed with SL data and transmitted. The SA may be referred to as an SL control channel.

(2) SL data channel (physical sidelink shared channel (PSSCH)) may be a resource pool through which the transmitting UE transmits user data. When the SA and SL data are multiplexed and transmitted together in the same resource unit, only the SL data channel except for the SA information may be transmitted in the resource pool for the SL data channel In other words, resource elements (REs) used to transmit the SA information in individual resource units in the SA resource pool may still be used to transmit the SL data in the resource pool of the SL data channel For example, the transmitting UE may map the PSSCH to consecutive PRBs and transmit the same.

(3) The discovery channel may be a resource pool used for the transmitting UE to transmit information such as the ID thereof. Through this channel, the transmitting UE may allow a neighboring UE to discover the transmitting UE.

Even when the SL signals described above have the same content, they may use different resource pools according to the transmission/reception properties of the SL signals. For example, even when the SL data channel or discovery message is the same among the signals, it may be classified into different resource pools according to determination of the SL signal transmission timing (e.g., transmission at the reception time of the synchronization reference signal or transmission by applying a predetermined TA at the reception time), a resource allocation scheme (e.g., the BS designates individual signal transmission resources to individual transmitting UEs or individual transmission UEs select individual signal transmission resources within the resource pool), signal format (e.g., the number of symbols occupied by each SL signal in a subframe, or the number of subframes used for transmission of one SL signal), signal strength from a BS, the strength of transmit power of an SL UE, and the like.

Hereinafter, resource allocation in the SL will be described.

FIG. 13 illustrates a procedure in which UEs perform V2X or SL communication according to a transmission mode. In various embodiments of the present disclosure, the transmission mode may be referred to as a mode or a resource allocation mode. Hereinafter, for simplicity, the transmission mode in LTE may be referred to as an LTE transmission mode, and the transmission mode in NR may be referred to as an NR resource allocation mode.

For example, FIG. 13-(a) illustrates a UE operation related to LTE transmission mode 1 or LTE transmission mode 3. Alternatively, for example, FIG. 13-(a) illustrates a UE operation related to NR resource allocation mode 1. For example, LTE transmission mode 1 may be applied to general SL communication, and LTE transmission mode 3 may be applied to V2X communication.

For example, FIG. 13-(b) illustrates a UE operation related to LTE transmission mode 2 or LTE transmission mode 4. Alternatively, for example, FIG. 13-(b) illustrates a UE operation related to NR resource allocation mode 2.

Referring to FIG. 13-(a), in LTE transmission mode 1, LTE transmission mode 3 or NR resource allocation mode 1, the BS may schedule an SL resource to be used by the UE for SL transmission. For example, the BS may perform resource scheduling for UE 1 through PDCCH (more specifically, downlink control information (DCI)), and UE 1 may perform V2X or SL communication with UE 2 according to the resource scheduling. For example, UE 1 may transmit sidelink control information (SCI) to UE 2 on a physical sidelink control channel (PSCCH), and then transmit data which is based on the SCI to UE 2 on a physical sidelink shared channel (PSSCH).

For example, in NR resource allocation mode 1, the UE may be provided with or allocated resources for one or more SL transmissions of a transport block (TB) from the BS through a dynamic grant. For example, the BS may provide a resource for transmission of the PSCCH and/or PSSCH to the UE using the dynamic grant. For example, the transmitting UE may report the SL hybrid automatic repeat request (HARQ) feedback received from the receiving UE to the BS. In this case, the PUCCH resource and timing for reporting the SL HARQ feedback to the BS may be determined based on an indication in the PDCCH through the BS is to allocate a resource for SL transmission.

For example, DCI may include a slot offset between DCI reception and the first SL transmission scheduled by the DCI. For example, the minimum gap between the DCI scheduling a SL transmission resource and the first scheduled SL transmission resource may not be shorter than the processing time of the corresponding UE.

For example, in NR resource allocation mode 1, the UE may be periodically provided with or allocated a resource set from the BS for a plurality of SL transmissions through a configured grant. For example, the configured grant may include configured grant type 1 or configured grant type 2. For example, the UE may determine a TB to be transmitted in each occasion indicated by a given configured grant.

For example, the BS may allocate SL resources to the UE on the same carrier, and may allocate SL resources to the UE on different carriers.

For example, an NR BS may control LTE-based SL communication. For example, the NR BS may transmit NR DCI to the UE to schedule an LTE SL resource. In this case, for example, a new RNTI for scrambling the NR DCI may be defined. For example, the UE may include an NR SL module and an LTE SL module.

For example, after the UE including the NR SL module and the LTE SL module receives NR SL DCI from the gNB, the NR SL module may transform the NR SL DCI to LTE DCI type 5A, and the NR SL module may deliver LTE DCI type 5A to the LTE SL module in units of X ms. For example, the LTE SL module may apply activation and/or release to the first LTE subframe Z ms after the LTE SL module receives LTE DCI format 5A from the NR SL module. For example, the X may be dynamically indicated using a field of DCI. For example, the minimum value of X may depend on the UE capability. For example, the UE may report a single value according to the UE capability. For example, X may be a positive number.

Referring to FIG. 13-(b), in LTE transmission mode 2, LTE transmission mode 4, or NR resource allocation mode 2, the UE may determine AN SL resource within the SL resources configured by the BS/network or the preconfigured SL resources. For example, the configured SL resources or the preconfigured SL resources may be a resource pool. For example, the UE may autonomously select or schedule a resource for SL transmission. For example, the UE may autonomously select a resource within the configured resource pool to perform SL communication. For example, the UE may select a resource within a selection window by performing a sensing and resource (re)selection procedure. For example, the sensing may be performed on a per sub-channel basis. In addition, UE 1, which has selected a resource within the resource pool, may transmit SCI to UE 2 through the PSCCH, and then transmit data, which is based on the SCI, to UE 2 through the PSSCH.

For example, a UE may assist in selecting an SL resource for another UE. For example, in NR resource allocation mode 2, the UE may receive a configured grant for SL transmission. For example, in NR resource allocation mode 2, the UE may schedule SL transmission of another UE. For example, in NR resource allocation mode 2, the UE may reserve an SL resource for blind retransmission.

For example, in NR resource allocation mode 2, UE 1 may indicate the priority of SL transmission to UE 2 using the SCI. For example, UE 2 may decode the SCI. UE 2 may perform sensing and/or resource (re)selection based on the priority. For example, the resource (re)selection procedure may include an operation of identifying candidate resources in a resource selection window by UE 2, and an operation of selecting, by UE 2, a resource for (re)transmission from among the identified candidate resources. For example, the resource selection window may be a time interval during which the UE selects the resource for SL transmission. For example, after UE 2 triggers resource (re)selection, the resource selection window may start at T1≥0. The resource selection window may be limited by the remaining packet delay budget of UE 2. For example, in the operation of identifying the candidate resources in the resource selection window by UE 2, a specific resource may be indicated by the SCI received by UE 2 from UE 1. When the L1 SL RSRP measurement value for the specific resource exceeds an SL RSRP threshold, UE 2 may not determine the specific resource as a candidate resource. For example, the SL RSRP threshold may be determined based on the priority of the SL transmission indicated by the SCI received by UE 2 from UE 1 and the priority of the SL transmission on the resource selected by UE 2.

For example, the L1 SL RSRP may be measured based on an SL demodulation reference signal (DMRS). For example, one or more PSSCH DMRS patterns may be configured or preconfigured for each resource pool in the time domain. For example, PDSCH DMRS configuration type 1 and/or type 2 may be the same as or similar to the frequency domain pattern of the PSSCH DMRS. For example, the exact DMRS pattern may be indicated by the SCI. For example, in NR resource allocation mode 2, the transmitting UE may select a specific DMRS pattern from among DMRS patterns configured or preconfigured for the resource pool.

For example, in NR resource allocation mode 2, based on the sensing and resource (re)selection procedure, the transmitting UE may perform initial transmission of a TB without reservation. For example, based on the sensing and resource (re)selection procedure, using the SCI associated with a first TB, the transmitting UE may reserve the SL resource for initial transmission of a second TB.

For example, in NR resource allocation mode 2, the UE may reserve a resource for feedback-based PSSCH retransmission through signaling related to previous transmission of the same TB. For example, the maximum number of SL resources reserved by one transmission including the current transmission may be 2, 3, or 4. For example, the maximum number of SL resources may be the same regardless of whether HARQ feedback is enabled. For example, the maximum number of HARQ (re)transmissions for one TB may be limited by configuration or pre-configuration. For example, the maximum number of HARQ (re)transmissions may be up to 32. For example, when the configuration or pre-configuration is not present, the maximum number of HARQ (re)transmissions may be unspecified. For example, the configuration or pre-configuration may be for the transmitting UE. For example, in NR resource allocation mode 2, HARQ feedback for releasing resources not used by the UE may be supported.

For example, in NR resource allocation mode 2, the UE may indicate to another UE one or more sub-channels and/or slots used by the UE, using the SCI. For example, the UE may indicate to another UE one or more sub-channels and/or slots reserved by the UE for PSSCH (re)transmission, using SCI. For example, the minimum allocation unit of the SL resource may be a slot. For example, the size of the sub-channel may be configured for the UE or may be preconfigured.

Hereinafter, sidelink control information (SCI) will be described.

Control information transmitted by the BS to the UE on the PDCCH may be referred to as downlink control information (DCI), whereas control information transmitted by the UE to another UE on the PSCCH may be referred to as SCI. For example, before decoding the PSCCH, the UE may be aware of the start symbol of the PSCCH and/or the number of symbols of the PSCCH. For example, the SCI may include SL scheduling information. For example, the UE may transmit at least one SCI to another UE to schedule the PSSCH. For example, one or more SCI formats may be defined.

For example, the transmitting UE may transmit the SCI to the receiving UE on the PSCCH. The receiving UE may decode one SCI to receive the PSSCH from the transmitting

UE.

For example, the transmitting UE may transmit two consecutive SCIs (e.g., 2-stage SCI) to the receiving UE on the PSCCH and/or the PSSCH. The receiving UE may decode the two consecutive SCIs (e.g., 2-stage SCI) to receive the PSSCH from the transmitting UE. For example, when the SCI configuration fields are divided into two groups in consideration of the (relatively) high SCI payload size, the SCI including a first SCI configuration field group may be referred to as first SCI or 1st SCI, and the SCI including a second SCI configuration field group may be referred to as second SCI or 2nd SCI. For example, the transmitting UE may transmit the first SCI to the receiving UE on the PSCCH. For example, the transmitting UE may transmit the second SCI to the receiving UE on the PSCCH and/or the PSSCH. For example, the second SCI may be transmitted to the receiving UE on the (independent) PSCCH, or may be piggybacked together with data and transmitted on the PSSCH. For example, the two consecutive SCIs may be applied for different transmissions (e.g., unicast, broadcast, or groupcast).

For example, the transmitting UE may transmit some or all of the following information to the receiving UE through SCI. Here, for example, the transmitting UE may transmit some or all of the following information to the receiving UE through the first SCI and/or the second SCI:

-   -   PSSCH and/or PSCCH related resource allocation information, for         example, the positions/number of time/frequency resources,         resource reservation information (e.g., periodicity); and/or     -   SL CSI report request indicator or SL (L1) RSRP (and/or SL (L1)         RSRQ and/or SL (L1) RSSI) report request indicator; and/or     -   SL CSI transmission indicator (or SL (L1) RSRP (and/or SL (L1)         RSRQ and/or SL (L1) RSSI) information transmission indicator)         (on PSSCH); and/or     -   MCS information; and/or     -   transmit power information; and/or     -   L1 destination ID information and/or L1 source ID information;         and/or     -   SL HARQ process ID information; and/or     -   new data indicator (NDI) information; and/or     -   redundancy version (RV) information; and/or     -   (transmission traffic/packet related) QoS information; e.g.,         priority information; and/or     -   SL CSI-RS transmission indicator or information on the number of         (transmitted) SL CSI-RS antenna ports;     -   Location information about the transmitting UE or location (or         distance/area) information about a target receiving UE (to which         a request for SL HARQ feedback is made); and/or     -   information about a reference signal (e.g., DMRS, etc.) related         to decoding and/or channel estimation of data transmitted on the         PSSCH, for example, information related to a pattern of a         (time-frequency) mapping resource of DMRS, rank information,         antenna port index information.

For example, the first SCI may include information related to channel sensing. For example, the receiving UE may decode the second SCI using the PSSCH DMRS. A polar code used for the PDCCH may be applied to the second SCI. For example, in the resource pool, the payload size of the first SCI may be the same for unicast, groupcast and broadcast. After decoding the first SCI, the receiving UE does not need to perform blind decoding of the second SCI. For example, the first SCI may include scheduling information about the second SCI.

In various embodiments of the present disclosure, since the transmitting UE may transmit at least one of SCI, the first SCI, and/or the second SCI to the receiving UE on the PSCCH, the PSCCH may be replaced/substituted with at least one of the SCI, the first SCI, and/or the second SCI. Additionally/alternatively, for example, the SCI may be replaced/substituted with at least one of the PSCCH, the first SCI, and/or the second SCI. Additionally/alternatively, for example, since the transmitting UE may transmit the second SCI to the receiving UE on the PSSCH, the PSSCH may be replaced/substituted with the second

Hereinafter, synchronization acquisition by an SL UE will be described.

In TDMA and FDMA systems, accurate time and frequency synchronization is essential. Inaccurate time and frequency synchronization may lead to degradation of system performance due to inter-symbol interference (ISI) and inter-carrier interference (ICI). The same is true for V2X. For time/frequency synchronization in V2X, a sidelink synchronization signal (SLSS) may be used in the PHY layer, and master information block-sidelink-V2X (MIB-SL-V2X) may be used in the RLC layer.

FIG. 14 illustrates a V2X synchronization source or reference to which the present disclosure is applicable.

Referring to FIG. 14, in V2X, a UE may be synchronized with a GNSS directly or indirectly through a UE (within or out of network coverage) directly synchronized with the GNSS. When the GNSS is configured as a synchronization source, the UE may calculate a direct subframe number (DFN) and a subframe number by using a coordinated universal time (UTC) and a (pre)determined DFN offset.

Alternatively, the UE may be synchronized with a BS directly or with another UE which has been time/frequency synchronized with the BS. For example, the BS may be an eNB or a gNB. For example, when the UE is in network coverage, the UE may receive synchronization information provided by the BS and may be directly synchronized with the BS. Thereafter, the UE may provide synchronization information to another neighboring UE. When a BS timing is set as a synchronization reference, the UE may follow a cell associated with a corresponding frequency (when within the cell coverage in the frequency), a primary cell, or a serving cell (when out of cell coverage in the frequency), for synchronization and DL measurement.

The BS (e.g., serving cell) may provide a synchronization configuration for a carrier used for V2X or sidelink communication. In this case, the UE may follow the synchronization configuration received from the BS. When the UE fails in detecting any cell in the carrier used for the V2X or sidelink communication and receiving the synchronization configuration from the serving cell, the UE may follow a predetermined synchronization configuration.

Alternatively, the UE may be synchronized with another UE which has not acquired synchronization information directly or indirectly from the BS or GNSS. A synchronization source and a preference may be preset for the UE. Alternatively, the synchronization source and the preference may be configured for the UE by a control message provided by the BS.

A sidelink synchronization source may be related to a synchronization priority. For example, the relationship between synchronization sources and synchronization priorities may be defined as shown in Tables 5 and 6. Tables 5 and 6 are merely an example, and the relationship between synchronization sources and synchronization priorities may be defined in various manners.

TABLE 5 BS-based synchronization (eNB/gNB-based Priority GNSS-based synchronization synchronization) P0 GNSS BS P1 All UEs directly All UEs directly synchronized synchronized with GNSS with BS P2 All UEs indirectly All UEs indirectly synchronized synchronized with GNSS with BS P3 All other UEs GNSS P4 N/A All UEs directly synchronized with GNSS P5 N/A All UEs indirectly synchronized with GNSS P6 N/A All other UEs

TABLE 6 Priority GNSS-based synchronization eNB/gNB-based synchronization P0 GNSS BS P1 All UEs directly synchronized All UEs directly synchronized with GNSS with BS P2 All UEs indirectly All UEs indirectly synchronized synchronized with GNSS with BS P3 BS GNSS P4 All UEs directly synchronized All UEs directly synchronized with BS with GNSS P5 All UEs indirectly All UEs indirectly synchronized synchronized with BS with GNSS P6 Remaining UE(s) with low Remaining UE(s) with low priority priority

In Table 5 or Table 6, PO may denote the highest priority, and P6 may denote the lowest priority. In Table 5 or Table 6, the BS may include at least one of a gNB or an eNB.

Whether to use GNSS-based synchronization or BS-based synchronization may be (pre)determined. In a single-carrier operation, the UE may derive its transmission timing from an available synchronization reference with the highest priority.

Vehicular Communications for ITS

An intelligent transport system (ITS) designed to utilize Vehicle-to-Everything (V2X) communication may mainly include an Access layer, a Network & Transport layer, a Facilities layer, an Application layer, a Security Management Entity, etc. V2X communication may be applied to various scenarios such as vehicle-to-vehicle (V2V) communication, V2N (or N2V) communication between vehicle and BS (base station), V2I (or I2V) communication between a vehicle and an RSU (Road Side Unit), I2I communication between one RSU and another RSU, a V2P (or P2V) communication between vehicle to person, and I2P (or P2I) communication between RSU and person. In this case, the vehicle, the BS (or eNB), the RSU, the person, etc., each of which serves as a subject of vehicle communication, will hereinafter be referred to as an ITS station.

FIG. 15 is a schematic diagram illustrating an ITS (intelligent transport system) station reference architecture.

Referring to FIG. 15, the ITS station reference architecture may include an access layer, a network & transport layer, a facilities layer, a security management entity, and an application layer that serves as the uppermost layer. Basically, the ITS station may operate to follow a layered OSI (OSI layer) model.

In detail, FIG. 16 is a conceptual diagram illustrating characteristics of the ITS station reference architecture based on the OSI model. Referring to FIG. 16, the access layer of the ITS station may correspond to an OSI Layer 1 (physical layer) and Layer 2 (data link layer), the network & transport layer of the ITS station may correspond to OSI Layer 3 (network layer) and Layer 4 (transport layer), and the facilities layer of the ITS station may correspond to an OSI Layer 5 (session layer), Layer 6 (presentation layer), and Layer 7 (application layer).

The application layer acting as the uppermost layer of the ITS station may actually implement and support a variety of use cases, and may be selectively used according to which one of the use cases is used. A management entity may serve to manage communication and operations of the ITS station as well as all the layers of the ITS station. The security entity may provide security services of all layers of the ITS station. The respective layers of the ITS station may exchange not only transmission (Tx) or reception (Rx) data to be used for V2X communication through an interface therebetween, but also additional information having various purposes with one another. The following description illustrates abbreviations of various interfaces.

MA: Interface between management entity and application layer

MF: Interface between management entity and facilities layer

MN: Interface between management entity and networking & transport layer

MI: Interface between management entity and access layer

FA: Interface between facilities layer and ITS-S applications

NF: Interface between networking & transport layer and facilities layer

IN: Interface between access layer and networking & transport layer

SA: Interface between security entity and ITS-S applications

SF: Interface between security entity and facilities layer

SN: Interface between security entity and networking & transport layer

SI: Interface between security entity and access layer

VRU-Collision Avoidance Guidance

In legacy technology, it is possible to estimate the risk of collision between a vulnerable road user (VRU) and a vehicle (i.e., an oncoming vehicle) approaching the VRU. When there is a high risk of collision between the VRU and the oncoming vehicle, only a collision risk warning message can be included in a safety message of the VRU, so that the resultant safety message including the collision risk warning message can be transmitted to a destination. In this case, although the vehicle having received the above safety message can sense the collision risk as described above, it is difficult for the vehicle to determine which task will be performed to reduce the degree of collision risk.

The present disclosure proposes a method for enabling the VRU to transmit a safety message by detecting the risk of collision with an oncoming vehicle so that the VRU provides the vehicle with a detailed method capable of performing collision avoidance between the VRU and the vehicle, thereby minimizing the risk of collision between the VRU and the vehicle.

The present disclosure proposes Vehicle-to-VRU communication technology in which a vulnerable road user (VRU) is considered. When each VRU device or associated application is activated, transmission of a first safety message may be started. Alternatively, the risk of collision between the VRU and the vehicle may be calculated. When the calculated collision risk exceeds a predetermined level, transmission of the VRU safety message may be started. Alternatively, the operation mode switches to a mode for starting signal transmission, so that transmission of the VRU safety message can be started in the transmission starting mode. Thereafter, transmission of the VRU safety message may be transmitted with a fixed or random transmission (Tx) interval, or the fixed or random Tx interval may be dynamically adjusted depending on a movement state of the VRU. The safety message transmitted by the VRU may include information such as a warning message indicating the collision risk, so that the risk of collision between the VRU and the vehicle can be minimized

Alternatively, when the VRU transmits the safety message, not only the safety message, but also the task to be performed by the vehicle to minimize the collision risk may be simultaneously provided to the vehicle. The present disclosure can significantly reduce the collision risk as compared to the case in which the VRU provides the vehicle with only the collision risk warning message.

Alternatively, the VRU may determine whether there is a risk of collision with vehicle(s), and may transmit a safety message according to the result of determination. In this case, the safety message may include collision risk warning information, detailed work information for reducing the collision risk, etc., so that the collision risk between the VRU and the vehicle can be minimized

Alternatively, a personal safety message (PSM) used in the legacy technology can be extended as will be described below, so that the VRU can minimize the collision risk between the VRU and the vehicle by providing the vehicle with the measured collision avoidance guide information. The constituent elements and data types for use in PSM are defined as shown in the following Table 7.

TABLE 7 Name Data type Value or description basicType PersonalDeviceUserType unavailable (0), aPEDESTRIAN (1), aPEDALCYCLIST (2), aPUBLICSAFETYWORKER (3), anANIMAL (4) secMark DSecond DSecond ::= INTEGER (0 . . . 65535)-- units of milliseconds msgCnt MsgCount MsgCount ::= INTEGER (0 . . . 127) id TempraryID TemporaryID ::= OCTET STRING (SIZE(4)) position Position3D lat Latitude, -- in 1/10th micro degrees long Longitude, -- in 1/10th micro degrees elevation Elevation OPTIONAL, -- in 10 cm units accuracy PositionalAccuracy semiMajor SemiMajorAxisAccuracy, semiMinor SemiMinorAxisAccuracy, orientation SemiMajorAxisOrientation speed Velocity Velocity ::= INTEGER (0 . . . 8191) -- Units of 0.02 m/s heading Heading Heading ::= INTEGER (0 . . . 28800) accelSet AccelerationSet4Way long, lat, vert, yaw pathHistory PathHistory initialPosition FullPositionVector OPTIONAL, currGNSSstatus GNSSstatus OPTIONAL, crumbData PathHistoryPointList, pathPrediction PathPrediction RadiusOfCurvature, Confidence propulsion PropelledInformation HumanPropelledType (unavailable, otherTypes, onFoot, skateboard, pushOrKickScooter, wheelchair) AnimalPropelledType (unavailable, otherTypes, animalMounted, animalDrawnCarriage) MotorizedPropelledType (unavailable, otherTypes, wheelchair, bicycle, scooter, selfBalancingDevice) useState Personal DeviceUsageState unavailable (0), other (1), idle (2), listeningToAudio (3), typing (4), calling (5), playingGames (6), reading (7), viewing (8), } (SIZE (9, . . .)) crossRequest PersonalCrossingRequest True = On (request crossing) False = Off (no request) crossState PersonalCrossingInProgress True = Yes, is in maneuver False = No clusterSize NumberOfParticipantsInCluster small (2~5) medium (6~10) large (10~) clusterRadius PersonalClusterRadius PersonalClusterRadius ::= INTEGER (0 . . . 100) -- units of meters eventResponderType PublicSafetyEventResponderWorkerType unavailable towOperator fireAndEMSWoker DOTWorker lawEnforcement hazmatResponder animalControlWorker otherPersonnel activityType PublicSafetyAndRoadWorkerActivity unavailable workingOnRoad settingUpClosures respondingToEvents directingTraffic otherActivities activitySubType PublicSafetyDirectingTraffic unavailable SubType policeAndTrafficOfficers trafficControlPersons railroadCrossingGuards civilDefenseNationalGuardMilitaryPolice emergencyOrganizationPersonnel highwayService (vehicle)Personnel assistType PersonalAssistive unavailable otherType vision hearing movement cognition sizing UserSizeAndBehaviour unavailable smallStature largeStature erraticMoving slowMoving attachment Attachment unavailable stroller bicycleTrailer cart wheelchair otherWalkAssistAttachments pet attachmentRadius AttachmentRadius AttachmentRadius ::= INTEGER (0 . . . 200) -- In LSB units of one decimeter animalType AnimalType unavailable serviceUse pet farm

Alternatively, the process of estimating the collision risk between the VRU and the vehicle is performed based on information transferred from the vehicle to the VRU. If there is a high risk of collision between the VRU and the vehicle based on the result of estimation, collision avoidance guide information may be added to the safety message transferred from the VRU.

Alternatively, collision avoidance guide information of the safety message transferred by the VRU may include values that are measured for collision risk estimation in the VRU as shown in the following Table 8.

TABLE 8 Name Data Type Value or Description collisionAvoidanceGuide CollisionAvoidanceGuideType guidedActions - This value defines a method for avoiding collision with the vehicle by the VRU. Each method will be described in more detail below. expectedCollisionInfo - This value defines expected collision information depending on the collision risk estimation result obtained by the VRU. The corresponding information may include predicted collision time information and predicted collision location information. The respective values will be described in more detail with reference to the following tables. guidedActionsDetail - This value defines detailed parameter values about the method for enabling the VRU to avoid collision with the vehicle according to the ‘guidesActions’ value. The respective parameters will be described in more detail with reference to the following tables.

‘CollisionAvoidanceGuide’ defined in Table 8 will be defined as follows according to ASN.1 format.

collisionAvoidanceGuide::=SEQUENCE {

guidedActions GuidedActions,—This parameter may refer to a method for enabling the VRU to avoid collision with vehicle.

expectedCollisionInfo ExpectedCollisionInfo,—Information about collision expected by the VRU

guidedActionsDetail GuidedActionsDetail,—Detailed information about the method for performing collision avoidance

. . .

}

Next, ‘guidedActions’ defined in sequence (SEQUENCE) of collision avoidance guide information may be defined as shown in the following Table 9. ‘guidedActions’ may be defined based on the content related to a method for minimizing the possibility of collision with the vehicle by the VRU that is configured to measure or estimate the collision risk between the VRU and the vehicle.

TABLE 9 Name Data Type Value or Description guidedActions GuidedActions ‘GuidedActions’ is defined as BIT STRING type. 2, 3, 4, and 5 bits can be analyzed by OR operation, and at least one value may be set to ‘1’. unavailable (0) - This means one case in which VRU does not find a value appropriate for ‘guidedActions’. other (1) - this means a vehicle behavior guide other than values defined below. stopImmediately (2) - Whereas VRU guides the safest motion of the vehicle in a manner that the vehicle should stop motion as soon as a safety message is received, the VRU physically recognizes that the vehicle cannot immediately stop motion. Thus, if the corresponding bit is set to ‘1’, VRU further guides ‘guidedMaxStoppingDistance’ value of ‘guidedActionsDetail’ information, so that the vehicle cannot exceed a maximum braking distance. decelerate (3) - Deceleration of the vehicle is recommended. When the corresponding bit is set to ‘1’, VRU provides ‘guidedMaxSpeed’ information as details information, thereby guiding a deceleration behavior instruction of the vehicle. changeLane (4) - This parameter recommends change of a vehicle lane. When the corresponding bit is set to ‘1’, the behavior instruction for changing the vehicle lane can be more precisely guided through guidedLaneChange or guidedLane of the detailed information. changeHeading (5) - Changing of the moving direction of the vehicle is recommended. If the corresponding ii set to ‘1’, the behavior instruction of the change of vehicle heading can be more precisely guided through ‘guidedHeadingChange’ value of details information.

For example, the value of ‘guided actions’ value defined in Table 9 may be defined as follows according to ASN.1 format.

GuidedActions::=BIT STRING {

unavailable (0),—Not specified

other (1),—Used for actions not defined below

stopImmediately (2)—This parameter recommends maximum deceleration to a vehicle receiving this message.

decelerate (3)—This parameter recommends the vehicle receiving this message to perform deceleration.

changeLane (4)—This parameter recommends the vehicle receiving this message to change lanes.

changeHeading (5)—This parameter recommends the vehicle receiving this message to change the heading direction.

. . .

} (SIZE (6, . . . ))

Subsequently, ‘expectedCollisionInfo’ defined in SEQUENCE of collision avoidance guide information can be defined as shown in the following Table 10. ‘expectedCollisionInfo’ may refer to a time domain and a range in which the risk of a collision between the VRU and the vehicle may occur based on vehicle information received from an oncoming vehicle while measuring the collision risk by the VRU.

TABLE 10 Name Data Type Value or Description expectedCollisionInfo ExpectedCollisionInfo expectedCollisionTime range - This parameter includes the start time and the end time where collision occurrence is expected. If only one time information is included, this parameter refers to the start time where collision is expected. expectedCollisionArea - This parameter defines the range information of an expected collision area. This parameter information may follow destination area information defined in DENM. This area may have a circular/ rectangular/elliptical shape. Confidence - This parameter defines the reliability of the result of collision risk estimation performed by VRU. This parameter can be represented in units of 0.5 percent.

The value of the expected collision info defined in Table 10 can be defined as follows according to the ASN.1 format.

ExpectedCollisionInfo::=SEQUENCE {

expectedCollisionTime SEQUENCE (SIZE(0 . . . 2)) OF TIME-OF-DAY—This parameter refers to the range of expected collision time.

expectedCollisionArea destinationArea—This parameter refers to the range of expected collision location.

confidence Confidence—0.5 percent unit

. . .

}

TABLE 11 Name Data Type Value or Description guidedActionsDetail GuidedActionsDetailType guidedMaxSpeed - This parameter defines a maximum value of the speed where avoidance of collision with vehicle is made available. The vehicle operates to reduce a speed to be slower than a target speed where the collision risk can be reduced. guidedMaxStoppingDistance - This parameter defines a maximum braking distance where collision avoidance is made available. The vehicle may operate to stop driving within a maximum braking distance so as to reduce the collision risk. guidedHeadingRange - This parameter defines the heading range where collision avoidance is made available. The vehicle may operate to change the heading direction within the corresponding range so as to reduce the collision risk. guidedLaneChange - This parameter defines the lane change direction for collision avoidance. The vehicle can change from a current lane to another change guided by VRU so as to reduce the collision risk. For example, ‘+1’ denotes that the vehicle moves from a current lane to the next right lane located at the right side of the current lane by a predetermined distance corresponding to one lane. guidedLane - This parameter defines the number(s) of lanes where collision avoidance is made available. The vehicle can change a current lane to a lane guided by the VRU so as to reduce the collision risk. If several lanes are guided, the vehicle selects the most favorable lane front its own moving direction, and moves the current lane to the selected lane.

The guided actions detail value defined in Table 11 can be defined as follows according to ASN.1 format.

guidedActionsDetail::=SEQUENCE {

guidedMaxSpeed Velocity—This parameter refers to a maximum speed where collision avoidance is made available.

guidedMaxStoppingDistance INTEGER—This parameter refers to a maximum braking distance where collision avoidance is made available.

guidedHeadingRange SEQUENCE (SIZE(2)) OF Heading—This parameter refers to the heading range where collision avoidance is made available.

guidedLaneChange INTEGER—This parameter refers to a lane change direction (right(+), left(−)) where collision avoidance is made available.

guidedLane INTEGER—This parameter refers to number(s) of vehicle lanes where collision avoidance is made available.

. . .

}

Meanwhile, the safety message may be included in a sidelink signal, so that the sidelink signal including the safety message can be transmitted to a destination. The safety message may be transmitted to another VRU, UE, RSU (road side unit), etc. through any one of a physical sidelink broadcast channel (PSBCH), a physical sidelink control channel (PSCCH), a physical sidelink shared channel (PSSCH), a physical sidelink discovery channel (PSDCH), a primary sidelink synchronization signal (PSSS), a secondary sidelink synchronization signal (SSSS), and a physical sidelink feedback channel (PSFCH). In the following description, for convenience of description, transmission or transfer of the safety message may indicate that the safety message is included in the sidelink signal so that the resultant sidelink signal is then transmitted.

The safety message may be transmitted by a VRU, a vehicle, RSU, UE, etc. In this case, the VRU may include a UE or another UE located in the vehicle.

FIGS. 16 and 17 are conceptual diagrams illustrating methods for transmitting the safety message including collision avoidance guide information.

Referring to FIG. 16, the VRU may discover the presence of a puddle in a left sidewalk block, and may attempt to perform temporary walking via a roadway, as represented by {circle around (1)}. On the other hand, at the location of {circle around (2)}, the vehicle is invisible to the eyes of the VRU.

The VRU may detect a signal received from the vehicle at the location of where the VRU enters the roadway, and may estimate the collision risk based on the detected signal.

The VRU may detect that there is a risk of collision with the oncoming vehicle at the location of {circle around (3)}, and may transmit a safety message to the vehicle according to the result of detected collision risk estimation. In this case, the safety message may include the following collision avoidance guide information.

In more detail, the collision avoidance guide information may include ‘guidedActions (001101)’ in which each of a value of ‘stop immediately’, a value of ‘decelerate’, and a value of ‘change heading’ is set to ‘1’. This ‘guidedActions (001101)’ information may recommend the vehicle to immediately stop operation. Otherwise, the ‘guidedActions (001101)’ information may recommend the vehicle to perform deceleration or to change the heading direction.

Alternatively, the collision avoidance guide information may include the value of ‘guidedHeadingRange’ when the change heading BIT STRING of guidedActions information is set to 1. In this case, the value of guidedHeadingRange may be set to the angle (a) as shown in FIG. 15.

Alternatively, the collision avoidance guide information may further include the value of guidedMaxSpeed when a ‘decelerate BIT STRING’ value of the guideActions constituent elements is set to ‘1’. The ‘guidedMaxSpeed’ value can be calculated based on the collision risk estimation measurement value in response to either the distance to the vehicle and/or the movement angle of the vehicle.

Referring to FIG. 17, each of the vehicle A and the other vehicle B is moving along a given path toward a destination thereof. At this time, a vulnerable road user (VRU) may be moving toward his or her destination. Here, at represented by {circle around (1)}, the VRU can estimate or sense the risk of collision with the vehicle A at a specific time and at a specific place.

Subsequently, the VRU can broadcast the safety message including collision avoidance guide information. The safety message may include information about a collision spot and collision time that are measured by the VRU. The corresponding message may be transmitted to both the vehicle A and the vehicle B. In this case, the vehicle A and the vehicle B may analyze the collision avoidance guide information included in the safety message received from the VRU. The vehicle A and the vehicle B may share the analyzed information and mobility information, so that each of the vehicles A and B can change a current path to another path where no collision with the other vehicle and the VRU occurs.

FIG. 18 is a flowchart illustrating a method for transmitting the safety message including collision avoidance guide information.

Referring to FIG. 18, the VRU may active the VRU application (S301). The VRU application may sense the presence of a vehicle (hereinafter referred to as an oncoming vehicle) approaching the VRU (S302). When the VRU detects the presence of the oncoming vehicle, the VRU may estimate or evaluate the presence or absence of collision risk based on mobility information received from the above vehicle (oncoming vehicle) (S303). At this time, the VRU may periodically receive updated mobility information from vehicles, and may consecutively evaluate the presence or absence of the collision risk based on the updated mobility information.

If the presence of the collision risk is detected, the VRU may transmit, to the vehicles, the safety message including at least one collision guide information from among the plurality of collision guide information segments defined in Tables 7 to 11 (S304, S305). The vehicles having received the safety message may control their movement directions or their movement speeds based on the above-mentioned collision guide information, and may provide the VRU with the updated information about the controlled movement direction and the controlled movement speed (S306, S307). In this case, the VRU may again perform the process for performing the collision risk estimation based on the above updated information.

Safety message transmission based on VRU clustering

In the legacy V2X communication environment, when the collision risk value of each of the VRUs is equal to or higher than a predetermined value, each of the VRUs can transmit the safety message. In this case, in the environment where VRUs are densely aggregated, the amount of communication traffic or the load of signals may excessively increase. In addition, all VRUs can perform the collision risk estimation procedure to transmit the safety message, and can consecutively consume power while simultaneously monitoring whether the collision risk value exceeds their threshold values.

In order to address the above issues, there is needed a method for enabling only some VRUs to transmit the safety message in the environment where the VRUs are densely aggregated. Specifically, in order to reduce the amount of communication traffic as compared to the legacy technology and to guarantee the same safety level as in the legacy technology, the present disclosure proposes a ‘Listen Before Send clustering’ scheme, a ‘Clustering by Area’ clustering scheme, a ‘Clustering by Collision Risk’ scheme, a ‘Clustering by Expected Collision Time and Area’ clustering scheme, and a ‘Clustering by Combined Conditions’ clustering scheme. In other words, the present disclosure can perform grouping or clustering of several VRUs using various schemes, and can transmit the safety message only to some VRUs configured to satisfy a specific condition within one cluster or one group. A detailed description thereof is as follows.

FIG. 19 is a conceptual diagram illustrating a method for enabling the VRU to determine whether to transmit a safety message based on a clustering scheme.

Referring to FIG. 19(a), the VRU may transmit the safety message at different time points. In this case, since several safety messages are transmitted within the space where VRUs are densely aggregated, the amount of communication traffic may greatly increase. In order to address the above issues, there is a need for only some VRUs from among the plurality of VRUs to transmit the safety messages within the area where VRUs are densely aggregated.

The above-mentioned method for transmitting the safety message based on clustering may be performed for each cycle where the safety message is transmitted, or may be performed at intervals of a specific time or at intervals of a specific message. For example, whenever the safety message is transmitted, the VRU may transmit the safety message according to the clustering-based safety message transmission scheme. Alternatively, the VRU may transmit the safety message based on the above clustering-based safety message transmission scheme at intervals of a predetermined time. For example, when the transmission cycle of the safety message is set to 0.1 s, the clustering-based safety message transmission may be performed whenever all the safety messages are transmitted, or may transmit the safety message based on the Listen-Before-End clustering scheme at intervals of a predetermined message.

The clustering-based safety message transmission scheme may include the ‘Listen Before Send clustering’ scheme, the ‘Clustering by Area’ clustering scheme, the ‘Clustering by Collision Risk’ scheme, a ‘Clustering by Expected Collision Time and Area’ scheme, and a ‘Clustering by Combined Conditions’ scheme. The above clustering schemes may determine whether to receive the safety message from the other VRU before the safety message is transmitted during a predetermined period, and/or may determine whether to transmit the safety message according to the result of monitoring of information included in the safety message received from the other VRU during the predetermined period. In this case, the predetermined period may be determined based on either a specific time or a transmission period in which the collision risk is sensed and the necessity of transmission of the safety message is determined due to the presence of collision risk. For example, the predetermined period may be set to a time period from a start time {where the V2X application is activated and the necessity of safety message transmission is determined based on the result of detected collision risk (or transmission period)} to the end time where the safety message is transmitted.

In accordance with the Listen-Before-Send clustering scheme, the VRU may determine whether to transmit the safety message by determining the presence or absence of the safety message that was received from another VRU for a predetermined time (alternatively, before reaching the transmission time of the corresponding safety message) prior to transmission of the safety message. For example, when the safety message received for the predetermined period exists, the VRU may not transmit the safety message thereof or may skip such transmission of the safety message.

Alternatively, during the predetermined period prior to transmission of the safety message (or before reaching the transmission time of the corresponding safety message), the VRU may determine whether to transmit the safety message based on the purpose and/or type of the safety message received from another VRU. For example, when the VRU is disposed adjacent to the other VRU having transmitted the received safety message (e.g., the VRU and the other VRU have the same zone ID), the safety message indicating the presence of VRU has already been transmitted at the position related to the VRU, so that the VRU need not transmit the safety message thereof, transmission of the safety message of the VRU may be stopped or dropped.

Referring to FIG. 19(b), the VRU may determine whether to transmit the safety message according to the ‘clustering by area’ scheme. In this case, the VRU may transmit the safety message including representative geographic area information (i.e., cluster area information), or may determine whether to transmit the safety message thereof based on geographic area information included in a safety message received from another VRU.

Specifically, when the VRU is located in the cluster area based on geographical area information included in the safety message received for the predetermined period, the VRU may not transmit the safety message thereof, or may drop transmission of the safety message. In contrast, when the safety message does not include information about the cluster area, or when the other VRU is not located in the cluster area, the above VRU can transmit the safety message thereof. Alternatively, when the VRU drops the safety message thereof, the VRU may transmit, to the other VRU, a message or signal about participation to the cluster area.

Referring to FIG. 19(c), the VRU may determine whether to transmit the safety message based on the ‘clustering by collision risk’ scheme. According to the ‘clustering by collision risk’ scheme, the VRU may transmit the safety message including a CR (Collision Risk) value that was estimated or calculated, or may determine whether to transmit the safety message thereof based on the CR value included in the safety message received from the other VRU.

Specifically, when the safety message is transmitted, the VRU may transmit the safety message including the CR value related to a condition of safety message transmission. In addition, the VRU may obtain the CR value related to the other VRU upon receiving the safety message from the other VRU, and may determine whether to transmit the safety message based on the obtained CR value. For example, when the estimated or calculated CR value is less than (or equal to or less than) the obtained CR value, the VRU may drop the safety message thereof without transmitting the safety message thereof. Alternatively, when the estimated or calculated CR value is higher than the obtained CR value, the VRU may transmit the safety message thereof including the estimated or calculated CR value.

Alternatively, the VRU may determine whether to transmit the safety message thereof based on the estimated or expected ‘clustering by expected collision time and area’ scheme. Specifically, the VRU may transmit the safety message including the collision area and the collision time (or collision area/time information) where occurrence of collision is expected, based on the surrounding environmental information (CAM, DENM, TNM, etc.) and the mobility information thereof. Alternatively, the VRU may determine whether to transmit the safety message thereof based on the collision area/time information obtained from the safety message received from the other VRU.

For example, when the collision area/time information obtained from the safety message received within the predetermined period corresponds to the expected collision area/time, the VRU may not transmit the safety message thereof or may drop the same safety message. Alternatively, when the collision area/time information received from the safety message received within the predetermined period (or before transmission of the safety message) does not correspond to the expected collision area/time, the VRU may transmit the safety message including the expected collision area/time information.

As described above, the VRU may transmit the safety message based on the above clustering scheme at intervals of a transmission time of the safety message or at intervals of a specific time period. In addition, the VRU may determine whether to transmit the safety message based on a combination of at least two schemes of the above-mentioned clustering-based safety message transmission schemes.

FIG. 20 is a flowchart illustrating a method for enabling the VRU to determine whether to transmit the safety message according to the clustering-based safety message transmission schemes.

Referring to FIG. 20, the VRU may transmit a first safety message at intervals of a preset transmission period (or may periodically transmit the first safety message when the estimated collision risk (CR) value is equal to or higher than a specific value) (S311). For example, the VRU may determine a time point where the above safety message will be transmitted, based on the above preset transmission period.

Subsequently, the VRU may monitor whether the safety message was received from the other VRU during a predetermined period (or until reaching the determined transmission (Tx) time point) (S313). Upon receiving the safety message from the other VRU, the VRU may determine whether to transmit a target safety message to be transmitted based on the received safety message (S315).

In more detail, a method for determining whether to transmit the safety message may be changed according to the above clustering-based safety message transmission schemes. Detailed examples thereof are as follows.

1) According to the ‘Listen before send’ scheme, when the safety message is not received during the predetermined period (before the VRU transmits the safety message thereof), transmission of the above safety message is allowed.

2) According to the ‘Clustering by area’ scheme, the VRU may determine whether to transmit the safety message based on the geographical area obtained from the second message. For example, when at least one safety message is received for the predetermined period and the VRU is located in the geographical area obtained from the safety message, the VRU may not allow transmission of the safety message. Alternatively, when the VRU is not located in the geographical area obtained from the safety message or when only the safety message not including information about the geographical area is received, the VRU may transmit the safety message. On the other hand, when the VRU desires to transmit a representative safety message only to a specific area, the VRU may transmit the safety message including information about the specific area.

3) According to the ‘clustering by collision risk’ scheme, the VRU may determine whether to transmit the safety message based on the CR (collision risk) value included in the safety message. For example, when at least one safety message is received for a predetermined period and the CR value obtained from the safety message is equal to or less than the CR value expected by the VRU, the VRU may transmit the safety message including the expected CR value. Alternatively, when the CR value obtained from the safety message exceeds the CR value expected by the VRU, the VRU may not transmit the safety message or may drop the safety message.

4) According to the ‘clustering by expected collision time and area’ scheme, the VRU may determine whether to transmit the safety message based on the collision area/time information included in the safety message. For example, when at least one safety message is received for a predetermined period and the collision area/time information obtained from the safety message is different from the other collision area/time information expected by the VRU, the VRU may transmit the safety message including information about the expected collision area/time information. Alternatively, when the collision area/time information obtained from the safety message corresponds to the collision area/time information expected by the VRU, or when only the safety message not including the collision area/time information is received, the VRU may not transmit the safety message or may drop the safety message.

Alternatively, the VRU may determine whether to transmit the safety message according to the clustering scheme based on a combination of the above schemes. For example, in the situation where the ‘clustering by area’ scheme and the ‘clustering by collision risk’ scheme are combined, when the VRU is located in the geographical area obtained from the received safety message or when the CR value obtained from the received safety message is higher than the VRU-expected CR value, the VRU may not transmit the safety message or may drop the safety message. Alternatively, when the VRU is located in the geographical area obtained from the received safety message, and when the CR value obtained from the received safety message is higher than the VRU-expected CR value, the VRU may not transmit the safety message or may drop the safety message.

Subsequently, when the above transmission conditions are satisfied and transmission of the first safety message is allowed, the VRU may transmit the first safety message at the determined transmission (Tx) time point (S317, S319).

Moreover, as described above, when the VRU determines not to transmit the safety message, the VRU may omit or skip transmission of the safety message at the determined transmission (Tx) time point of the determined safety message. The VRU may again determine whether to resume transmission of the safety message according to the above-mentioned scheme during a predetermined time cycle from the above transmission (Tx) time point of the above safety message to the transmission (Tx) time point of the next safety message. Alternatively, when the VRU does not transmit the safety message or drops the safety message, the VRU may stop transmission of the safety message during a predetermined threshold time. After lapse of the predetermined threshold time, the VRU may determine whether to resume transmission of the safety message according to the above-mentioned schemes.

On the other hand, according to the schemes for transmitting the clustering-based safety message, when the VRU does not receive a general safety message, a safety message including information about a specific area, or a safety message including specific collision area/time information during a predetermined period (or until transmission of the safety message), transmission of the safety message of the VRU can be allowed.

Alternatively, when the VRU receives at least one safety message during the predetermined period, the VRU may obtain specific information included in the received safety message, and may determine whether to transmit the safety message based on the obtained specific information. In this case, the specific information may be determined based on the scheme for transmitting the clustering-based safety message.

Coordinated Methods for Area Based Clustering

Based on the clustering-based safety message transmission scheme, the following signaling scheme may be considered.

Specifically, according to the method for enabling the vehicle/RSU to perform signaling of the VRU clustering area, the vehicle or RSU may designate the VRU clustering area, and may perform VRU signaling for the designated area. Information related to a VRU cluster area designated by the vehicle may include the shape, size, and location of the clustering area as shown in the following Table 12.

TABLE 12 Name Data Type Value or Description VRUclusterArea VRUClusterAreaType shape - This parameter represents the shape of a cluster, and has any one of circular/rectangular/ elliptical values. size - This parameter represents the size of area defined by the shape of the cluster. For example, if ‘shape = circular’ is given, ‘size’ is denoted by the diameter(R) value. location - This parameter represents the location of the clustering area defined according to the cluster shape. For example, if ‘shape = circular’ is given, ‘location’ is denoted by the center (latitude, longitude) of the circle.

FIGS. 21 and 22 are conceptual diagrams illustrating a method for enabling the VRU to determine whether to transmit the safety message based on a clustering related signal transmitted by a vehicle or a road side unit (RSU).

When clustering is not performed, the plurality of VRUs can transmit the safety message without execution of VRU clustering.

Referring to FIG. 21, the vehicle or VRU may designate or determine the VRU clustering areas A, B and C, and may perform signaling of the signal including information related to VRU cluster areas. VRUs belonging to the clustering area designated by the vehicle or VRU may select a representative VRU through the above-mentioned distributed scheme (or the clustering-based safety message transmission scheme) as shown in FIGS. 19 and 20. In this case, the VRU serving as the representative VRU may transmit the safety message, and the remaining VRUs may stop transmission of the safety message.

Alternatively, the vehicle may designate or determine the VRU clustering areas, and may determine a representative VRU for each VRU clustering area. The vehicle may perform signaling of both the designated VRU clustering area and a signal including ID information of the representative VRU determined in response to each VRU clustering area. In this case, only the representative VRU designated by the vehicle can transmit the safety message within each VRU clustering area. In this case, the representative selection procedure according to the above-mentioned distributed scheme may be omitted.

Specifically, the vehicle or RSU may designate a representative VRU for each cluster area by applying information defined in Table 13 to the representative VRU of the VRU cluster area.

TABLE 13 Name Data Type Value or Description RepVRU RepVRUType shape - This parameter represents the shape of a representative VRU area within the cluster area, and has any one of circular/rectangular/elliptical values. size - This parameter represents the shape of the area defined according to the shape of a representative VRU area. For example, if ‘shape = circular’ is given, ‘size’ is denoted by the diameter(R) value. location - This parameter represents the location of the area defined according to the shape of the representative VRU area. For example, if ‘shape = circular’ is given, ‘location’ is denoted by the center (latitude, longitude) of the circle. VRUDeviceID - This parameter represents an ID of the representative VRU device. When the vehicle or RSU has already recognized the device ID information of the representative VRU, signaling can be performed using the VRUDeviceID value.

Referring to FIG. 22, the VRU may determine whether to transmit the safety message based on the cluster information. The procedure for determining whether to transmit the safety message based on the cluster information may be performed every transmission cycle where transmission of the safety message is needed, or may be performed within a portion of the transmission (Tx) cycle where the above safety message is transmitted. For example, when the safety message is periodically transmitted at intervals of 0.1 s, the determination procedure may be performed at intervals of 0.1 s, or may be performed at intervals of a specific period (e.g., 0.2 s, 0.3s , 0.5 s, etc.) corresponding to a multiple of 0.1 s.

The VRU may activate the VRU application (S401). When the VRU application is activated, the VRU may determine not only the transmission period where the safety message will be transmitted, but also the transmission (Tx) time point where the safety message will be transmitted. Alternatively, the VRU may determine which one of Tx periods of the determined safety message will be used to perform the above determination procedure.

Subsequently, the VRU may receive configuration information (or configuration information related to VRU application) related to transmission of the safety message from the vehicle, the RSU, and/or the network (S403). The above configuration information may include cluster information related to clustering. Alternatively, the configuration information may further include not only information about the period where the operation of determining whether to transmit the safety message based on the cluster information is performed, but also information about the method for transmitting the safety message based on specific clustering.

When cluster information is included in the configuration information related to transmission of the safety message, the VRU may determine whether to transmit the safety message based on the cluster information. Specifically, it can be determined whether the VRU is located in the cluster area included in the above cluster information based on the acquired or measured geographical information (S403). Alternatively, when the VRU is located in the cluster area corresponding to the cluster information, the VRU may determine the representative selection procedure related to transmission or non-transmission of the safety message. Meanwhile, when the VRU is not located in the cluster area corresponding to the cluster information, the VRU may transmit the safety message at the time point determined irrespective of the representative selection procedure.

Subsequently, when the VRU is located in the cluster area, the procedure for selecting the distributed representative VRU (or the procedure for selecting the representative VRU according to the clustering-based safety message transmission scheme) may be performed (S404). In more detail, when the procedure for selecting the distributed representative VRU is performed, it is determined whether the VRU is a representative VRU of the cluster area based on at least one of the ‘listen before send’ clustering scheme, the ‘clustering by area’ scheme, the ‘clustering by collision risk’ scheme, the ‘clustering by expected collision time and area’ scheme, and the ‘clustering by combined conditions’ scheme. Information about which one of the above-mentioned clustering schemes will be used by the VRU may be instructed through the cluster information or the configuration information (or control information).

Subsequently, when the VRU is selected as the representative VRU, the VRU may generate the safety message including information corresponding to the currently-used clustering scheme from among the collision risk (CR) value, the geographical area information, and the collision area/time information (S405), and may transmit or broadcast the generated safety message (S406).

Alternatively, when the VRU is not selected as the representative VRU, the VRU performs steps S402 to S404, so that the VRU cannot transmit the safety message at the determined transmission (Tx) time point and can again determine whether to transmit the safety message within the next period.

Various embodiments for enabling the VRU located in the cluster area included in the cluster information to select the representative VRU (S404) will hereinafter be described with reference to the attached drawings.

In the VRU representative selection step S404, the VRU may monitor whether the safety messages of other VRUs have been received for a predetermined period (or before the VRU transmits the safety message thereof). After the VRU receives the safety message from the other VRU, it can be determined whether the VRU can be selected as its own representative VRU based on the received safety message.

According to the ‘Listen before send’ clustering scheme, the VRU may determine whether or not the representative VRU can be selected based on the presence or absence of the safety message received from the other VRU during the predetermined period (or before the transmission (Tx) time point where the VRU transmits the safety message). For example, when the safety message transmitted from the other VRU is not received within the predetermined period, the VRU can be selected as a representative VRU for the cluster area. On the other hand, regardless of whether transmission (Tx) resources of the safety message transmitted from the VRU overlap transmission (Tx) resources of the safety message transmitted from the other VRU, it can be determined whether to transmit the VRU safety message.

Alternatively, according to the ‘clustering by area’ scheme, it can be determined whether the VRU can be selected as a representative VRU for the cluster area based on geographical area information included in the safety message transmitted from the other VRU. For example, when the safety message including geographical area information belonging to the above cluster area is not received within the predetermined period (or until reaching the transmission (Tx) time point of the VRU safety message), the VRU may be selected as a representative VRU for the cluster area. Alternatively, upon receiving the safety message including geographical area information belonging to the cluster area, it can be determined that the VRU is selected as a representative VRU for the cluster area based on the received safety message.

Alternatively, according to the ‘clustering by collision risk’ scheme, it can be determined whether the VRU is selected as a representative VRU based on the collision risk (CR) value included in the received safety message. For example, when the CR value included in at least one safety message received for the predetermined period is less than the CR value calculated by the VRU, it can be determined that the VRU is selected as a representative VRU within the cluster area.

Alternatively, according to the ‘clustering by expected collision time and area’ scheme, it can be determined whether the VRU is selected as a representative VRU based on the collision area/time information obtained from the safety message received from the other VRU, during the predetermined period. For example, when the collision area/time information expected by the VRU is matched to the collision area/time information obtained from the received safety message, it can be determined that the VRU is selected as a representative VRU for the cluster area. Alternatively, when the VRU-expected collision area/time information is not matched to the obtained collision area/time information, it can be determined that the VRU is selected as a representative VRU for the cluster area.

Alternatively, the configuration information or the control information may further include instruction information for indicating the clustering scheme. That is, the instruction information may instruct at least one of the ‘Listen before send’ clustering scheme, the ‘clustering by area’ scheme, the ‘clustering by collision risk’ scheme, and the ‘clustering by expected collision time and area’ scheme. In this case, the VRU may determine whether to transmit the safety message based on specific information from among the safety messages of the other VRUs according to the scheme instructed by the instruction information.

In addition, when the VRU transmits the safety message as the representative VRU, the VRU may determine specific information to be included in the safety message according to the above instruction information. For example, when the instruction information indicates the ‘clustering by area’ scheme, the VRU may include the cluster area information in the safety message, and may then transmit the resultant safety message. Alternatively, when the instruction information indicates the ‘clustering by collision risk’ scheme, the VRU may include the CR value in the safety message, and may then transmit the resultant safety message.

Alternatively, the vehicle may further include at least one selection information segment for designating the representative VRU in the configuration information or in the cluster information. In this case, it can be determined whether each of the VRUs corresponds to a VRU corresponding to the selection information, instead of the VRU selection procedure affected according to whether the safety message of the other VRU was received for the predetermined period, so that the VRU can determine whether to transmit the safety message based on the result of determination.

Specifically, the vehicle (or VRU) may include ID information (or selection information) for a representative VRU scheduled to perform safety message transmission for each cluster area. At this time, the VRU may determine the cluster area corresponding to the VRU location (S403), and may obtain ID information corresponding to the determined cluster area. In this case, the VRU may determine whether its own ID information is matched to the obtained ID information, so that the VRU can perform the procedure (S404) related to selection of the representative VRU. In this case, the VRU may determine whether its own ID information corresponds to the obtained ID information, so that the VRU can perform the procedure (S404) related to the representative VRU. For example, when the VRU ID information corresponds to the obtained ID information, the VRU can transmit the safety message. In contrast, when the VRU ID information is different from the obtained ID information, transmission of the safety message is not allowed.

Meanwhile, the configuration information, the cluster information, and the control information may be transmitted not only to the vehicle or RSU, but also to the VRU.

FIGS. 23 and 24 are conceptual diagrams illustrating a method for enabling the VRU to determine whether to transmit the safety message according to a collision risk-based clustering scheme.

The VRU may receive configuration information (or configuration information related to VRU application) related to transmission of the safety message from the vehicle, RSU, and/or the network. The configuration information may include the cluster information. Alternatively, the configuration information may further include information about the period where a determination of whether to transmit the safety message is made, and information about the clustering scheme related to the determination of whether to transmit the safety message.

In this case, the cluster information may include the CR (collision risk) reference value related to representative selection of the VRU clustering designated by the vehicle or RSU. The cluster information may include information defined in the following Table 14.

TABLE 14 Name Data Type Value or Description CRofRepVRU CRofRepVRUType CollisionRisk - CR (collision risk) reference value of a representative VRU of VRU clustering designated by vehicle.

Referring to FIG. 23, the vehicle may transmit, to the plurality of VRUs, the message including cluster information where the CR reference value (e.g., 5) of the sending representative VRU is designated. Before the representative VRU of the VRU cluster is selected, each of the VRUs can transmit the safety message, so that a congestion situation may occur. Upon receiving the message including the cluster information, the VRU may compare the measured CR value with the CR reference value included in the cluster information. When the measured VR value is higher than the CR reference value, the VRU may be determined to be a representative VRU of the cluster, and may transmit the safety message. In contrast, when the measured value is less than the CR reference value, the VRU may not transmit the safety message or may drop the safety message based on the clustering.

Subsequently, the VRU serving as a representative VRU of the cluster may transmit the safety message including the measured CR value. Based on the CR value included in the safety message, the vehicle may change the CR reference value, and may include the changed CR reference value in the cluster information, so that the vehicle can transmit the message including the resultant cluster information. Specifically, the vehicle may determine whether to change the CR reference value based on the number of the safety messages. When the number of the safety messages (each including the CR value) received from the peripheral VRU is equal to or higher than the predetermined number of safety messages, the CR reference value can be changed to a higher CR reference value. For example, the vehicle may increase the CR reference value to a higher CR reference value, so that the number of representative VRUs, each of which is configured to transmit the safety message, can be reduced.

Referring to FIG. 24, the VRU may determine whether to transmit the safety message based on the cluster information. The procedure of transmitting the safety message based on the cluster information may be performed every transmission period where transmission of the safety message is needed, or may be performed in some parts of the transmission (Tx) period where transmission of the safety message is performed. For example, when the safety message is periodically transmitted at intervals of 0.1 s, the transmission procedure based on the cluster information may be performed at intervals of 0.1 s, or may be performed at intervals of a specific period (e.g., 0.2 s, 0.3s, 0.5 s, etc.) corresponding to a multiple of 0.1 s.

First, the VRU may activate the VRU application (S411). When the VRU application is activated, the VRU may determine the transmission (Tx) period and the Tx time point where the safety message will be transmitted. Alternatively, the VRU may determine which one of transmission (Tx) periods of the determined safety message will be used to perform the determination procedure.

Subsequently, the VRU may receive the configuration information (or the configuration information related to VRU application) related to transmission of the safety message from the vehicle, RSU, and/or the network (S412). The configuration information may include cluster information related to clustering in the configuration information related to transmission of the safety message. The cluster information may include the CR reference value related to the representative VRU of clustering.

Thereafter, the VRU may estimate or calculate the VR value thereof (S413). The VRU may calculate the CR value related to the possibility of collision risk based on CAM, DENM, TNM, PSM, and mobility information received from the peripheral vehicle and/or the other VRU. For example, the CR value may be matched to the CR possibility value that is calculated by the predetermined algorithm based on mobility information (or measured status information) and PSM, CAM (Cooperative Awareness Message), DENM (Decentralized Environmental Notification Message), and TNM (Threat Notification Message) received from other VRUs (or UE, vehicle). For example, the CR value may correspond to a value for a likelihood that a collision calculated by a predetermined algorithm is likely to occur based on its mobility information (or measured state information) and another VRU (or measured state information) and another VRU (or, UE, vehicle). For example, when the collision probability is set to 50%, the CR value may be set to 5. When the collision probability is set to 60%, the CR value may be set to 6.

Subsequently, the VRU may compare its own CR value with the CR reference value included in the cluster information (S414). When the calculated CR value is equal to or higher than the CR reference value, the VRU may generate the safety message (S415), and may transmit the generated safety message (S416).

Alternatively, when the calculated CR value is less than the CR reference value, the VRU may not transmit the safety message, and may compare the estimated CR value with the CR reference value in association with transmission or non-transmission of the safety message (S412 to S414).

Communication System Example to Which the Present Disclosure is Applied

Although not limited thereto, various descriptions, functions, procedures, proposals, methods, and/or operational flow charts of the present disclosure disclosed in this document may be applied to various fields requiring wireless communication/connection (5G) between devices.

Hereinafter, it will be illustrated in more detail with reference to the drawings. In the following drawings/description, the same reference numerals may exemplify the same or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise indicated.

FIG. 25 illustrates a communication system applied to the present disclosure.

Referring to FIG. 25, a communication system 1 applied to the present disclosure includes wireless devices, Base Stations (BSs), and a network. Herein, the wireless devices represent devices performing communication using Radio Access Technology (RAT) (e.g., 5G New RAT (NR)) or Long-Term Evolution (LTE)) and may be referred to as communication/radio/5G devices. The wireless devices may include, without being limited to, a robot 100 a, vehicles 100 b-1 and 100 b-2, an eXtended Reality (XR) device 100 c, a hand-held device 100 d, a home appliance 100 e, an Internet of Things (IoT) device 100 f, and an Artificial Intelligence (AI) device/server 400. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. Herein, the vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). The home appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include a sensor and a smartmeter. For example, the BSs and the network may be implemented as wireless devices and a specific wireless device 200 a may operate as a BS/network node with respect to other wireless devices.

The wireless devices 100 a to 100 f may be connected to the network 300 via the BSs 200. An AI technology may be applied to the wireless devices 100 a to 100 f and the wireless devices 100 a to 100 f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. Although the wireless devices 100 a to 100 f may communicate with each other through the BSs 200/network 300, the wireless devices 100 a to 100 f may perform direct communication (e.g., sidelink communication) with each other without passing through the BSs/network. For example, the vehicles 100 b-1 and 100 b-2 may perform direct communication (e.g. Vehicle-to-Vehicle (V2V)/Vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b, or 150 c may be established between the wireless devices 100 a to 100 f/BS 200, or BS 200/BS 200. Herein, the wireless communication/connections may be established through various RATs (e.g., 5G NR) such as uplink/downlink communication 150 a, sidelink communication 150 b (or, D2D communication), or inter BS communication (e.g. relay, Integrated Access Backhaul (IAB)). The wireless devices and the BSs/the wireless devices may transmit/receive radio signals to/from each other through the wireless communication/connections 150 a and 150 b. For example, the wireless communication/connections 150 a and 150 b may transmit/receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, and resource mapping/demapping), and resource allocating processes, for transmitting/receiving radio signals, may be performed based on the various proposals of the present disclosure.

Examples of Wireless Devices to Which the Present Disclosure is Applied

FIG. 26 illustrates a wireless device applicable to the present disclosure.

Referring to FIG. 26, a first wireless device 100 and a second wireless device 200 may transmit radio signals through a variety of RATs (e.g., LTE and NR). Herein, {the first wireless device 100 and the second wireless device 200} may correspond to {the wireless device 100 x and the BS 200} and/or {the wireless device 100 x and the wireless device 100 x} of FIG. 25.

The first wireless device 100 may include one or more processors 102 and one or more memories 104 and additionally further include one or more transceivers 106 and/or one or more antennas 108. The processor(s) 102 may control the memory(s) 104 and/or the transceiver(s) 106 and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor(s) 102 may process information within the memory(s) 104 to generate first information/signals and then transmit radio signals including the first information/signals through the transceiver(s) 106. The processor(s) 102 may receive radio signals including second information/signals through the transceiver 106 and then store information acquired by processing the second information/signals in the memory(s) 104. The memory(s) 104 may be connected to the processor(s) 102 and may store a variety of information related to operations of the processor(s) 102. For example, the memory(s) 104 may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) 102 or for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. Herein, the processor(s) 102 and the memory(s) 104 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s) 106 may be connected to the processor(s) 102 and transmit and/or receive radio signals through one or more antennas 108. Each of the transceiver(s) 106 may include a transmitter and/or a receiver. The transceiver(s) 106 may be interchangeably used with Radio Frequency (RF) unit(s). In the present disclosure, the wireless device may represent a communication modem/circuit/chip.

Specifically, the UE may include a processor 102 and a memory 104 that are connected to the RF transceiver. The memory 104 may include at least one program capable of performing the operation related to the embodiments shown in FIGS. 15 to 23.

The processor 102 may measure status information including mobility information, and may receive a first sidelink signal including control information. Based on not only the control information having cluster area information, but also status information having location information belonging to the cluster area, the processor 102 may monitor whether a third sidelink signal is received from other UEs for a predetermined period, and may determine whether to transmit the second sidelink signal based on the result of monitoring. The processor 102 may perform the embodiments related to transmission or non-transmission of the safety message based on the clustering shown in FIGS. 16 to 24, based on the program stored in the memory 104.

Alternatively, the chip set including the processor 102 and the memory 104 may be configured. In this case, the chip set may include at least one processor, and at least one memory operatively connected to the at least one processor and configured to store instructions such that the at least one processor performs specific operations by executing the instructions. The specific operations may include measuring status information including mobility information, receiving a first sidelink signal including control information, monitoring whether third sidelink signals transmitted from other UEs have been received for the predetermined period based on the control information having the cluster area information and the status information having location information belonging to the cluster area, and determining whether to transmit the second sidelink signal based on the result of monitoring. In addition, the above operations may perform embodiments related to transmission or non-transmission of the safety message based on the clustering described in FIGS. 16 to 24, based on the program stored in the memory 104.

Alternatively, a computer-readable storage medium is configured to store at least one computer program including instructions such that at least one processor performs specific operations by executing the instructions. The specific operations may include measuring status information including mobility information, receiving a first sidelink signal including control information, monitoring whether third sidelink signals transmitted from other UEs have been received for the predetermined period based on the control information having the cluster area information and the status information having location information belonging to the cluster area, and determining whether to transmit the second sidelink signal based on the result of monitoring. In addition, the above operations may perform embodiments related to transmission or non-transmission of the safety message based on the clustering described in FIGS. 16 to 24, based on the program stored in the memory 104. In addition, the computer program may include programs capable of performing operations of the embodiments related to transmission or non-transmission of the safety message based on the clustering described in FIGS. 16 to 24.

The second wireless device 200 may include one or more processors 202 and one or more memories 204 and additionally further include one or more transceivers 206 and/or one or more antennas 208. The processor(s) 202 may control the memory(s) 204 and/or the transceiver(s) 206 and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor(s) 202 may process information within the memory(s) 204 to generate third information/signals and then transmit radio signals including the third information/signals through the transceiver(s) 206. The processor(s) 202 may receive radio signals including fourth information/signals through the transceiver(s) 106 and then store information acquired by processing the fourth information/signals in the memory(s) 204. The memory(s) 204 may be connected to the processor(s) 202 and may store a variety of information related to operations of the processor(s) 202. For example, the memory(s) 204 may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) 202 or for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. Herein, the processor(s) 202 and the memory(s) 204 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s) 206 may be connected to the processor(s) 202 and transmit and/or receive radio signals through one or more antennas 208. Each of the transceiver(s) 206 may include a transmitter and/or a receiver. The transceiver(s) 206 may be interchangeably used with RF unit(s). In the present disclosure, the wireless device may represent a communication modem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 will be described more specifically. One or more protocol layers may be implemented by, without being limited to, one or more processors 102 and 202. For example, the one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, and SDAP). The one or more processors 102 and 202 may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Unit (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. The one or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. The one or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document and provide the generated signals to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive the signals (e.g., baseband signals) from the one or more transceivers 106 and 206 and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document.

The one or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or more processors 102 and 202. The descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software and the firmware or software may be configured to include the modules, procedures, or functions. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be included in the one or more processors 102 and 202 or stored in the one or more memories 104 and 204 so as to be driven by the one or more processors 102 and 202. The descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software in the form of code, commands, and/or a set of commands

The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and/or commands The one or more memories 104 and 204 may be configured by Read-Only Memories (ROMs), Random Access Memories (RAMs), Electrically Erasable Programmable Read-Only Memories (EPROMs), flash memories, hard drives, registers, cash memories, computer-readable storage media, and/or combinations thereof. The one or more memories 104 and 204 may be located at the interior and/or exterior of the one or more processors 102 and 202. The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 through various technologies such as wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, control information, and/or radio signals/channels, mentioned in the methods and/or operational flowcharts of this document, to one or more other devices. The one or more transceivers 106 and 206 may receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document, from one or more other devices. For example, the one or more transceivers 106 and 206 may be connected to the one or more processors 102 and 202 and transmit and receive radio signals. For example, the one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may transmit user data, control information, or radio signals to one or more other devices. The one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may receive user data, control information, or radio signals from one or more other devices. The one or more transceivers 106 and 206 may be connected to the one or more antennas 108 and 208 and the one or more transceivers 106 and 206 may be configured to transmit and receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document, through the one or more antennas 108 and 208. In this document, the one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). The one or more transceivers 106 and 206 may convert received radio signals/channels etc. from RF band signals into baseband signals in order to process received user data, control information, radio signals/channels, etc. using the one or more processors 102 and 202. The one or more transceivers 106 and 206 may convert the user data, control information, radio signals/channels, etc. processed using the one or more processors 102 and 202 from the base band signals into the RF band signals. To this end, the one or more transceivers 106 and 206 may include (analog) oscillators and/or filters.

Examples of Wireless Devices to Which the Present Disclosure is Applied

FIG. 27 illustrates another example of a wireless device applied to the present disclosure. The wireless device may be implemented in various forms according to a use-case/service (refer to FIG. 25)

Referring to FIG. 27, wireless devices 100 and 200 may correspond to the wireless devices 100 and 200 of FIG. 26 and may be configured by various elements, components, units/portions, and/or modules. For example, each of the wireless devices 100 and 200 may include a communication unit 110, a control unit 120, a memory unit 130, and additional components 140. The communication unit may include a communication circuit 112 and transceiver(s) 114. For example, the communication circuit 112 may include the one or more processors 102 and 202 and/or the one or more memories 104 and 204 of FIG. 26. For example, the transceiver(s) 114 may include the one or more transceivers 106 and 206 and/or the one or more antennas 108 and 208 of FIG. 26. The control unit 120 is electrically connected to the communication unit 110, the memory 130, and the additional components 140 and controls overall operation of the wireless devices. For example, the control unit 120 may control an electric/mechanical operation of the wireless device based on programs/code/commands/information stored in the memory unit 130. The control unit 120 may transmit the information stored in the memory unit 130 to the exterior (e.g., other communication devices) via the communication unit 110 through a wireless/wired interface or store, in the memory unit 130, information received through the wireless/wired interface from the exterior (e.g., other communication devices) via the communication unit 110.

The additional components 140 may be variously configured according to types of wireless devices. For example, the additional components 140 may include at least one of a power unit/battery, input/output (I/O) unit, a driving unit, and a computing unit. The wireless device may be implemented in the form of, without being limited to, the robot (100 a of FIG. 25), the vehicles (100 b-1 and 100 b-2 of FIG. 25), the XR device (100 c of FIG. 25), the hand-held device (100 d of FIG. 25), the home appliance (100 e of FIG. 25), the IoT device (100 f of FIG. 25), a digital broadcast terminal, a hologram device, a public safety device, an MTC device, a medicine device, a fintech device (or a finance device), a security device, a climate/environment device, the AI server/device (400 of FIG. 25), the BSs (200 of FIG. 25), a network node, etc. The wireless device may be used in a mobile or fixed place according to a use-example/service.

In FIG. 27, the entirety of the various elements, components, units/portions, and/or modules in the wireless devices 100 and 200 may be connected to each other through a wired interface or at least a part thereof may be wirelessly connected through the communication unit 110. For example, in each of the wireless devices 100 and 200, the control unit 120 and the communication unit 110 may be connected by wire and the control unit 120 and first units (e.g., 130 and 140) may be wirelessly connected through the communication unit 110. Each element, component, unit/portion, and/or module within the wireless devices 100 and 200 may further include one or more elements. For example, the control unit 120 may be configured by a set of one or more processors. As an example, the control unit 120 may be configured by a set of a communication control processor, an application processor, an Electronic Control Unit (ECU), a graphical processing unit, and a memory control processor. As another example, the memory 130 may be configured by a Random Access Memory (RAM), a Dynamic RAM (DRAM), a Read Only Memory (ROM)), a flash memory, a volatile memory, a non-volatile memory, and/or a combination thereof.

Hereinafter, an example of implementing FIG. 27 will be described in detail with reference to the drawings.

Examples of Mobile Devices to Which the Present Disclosure is Applied

FIG. 28 illustrates a hand-held device applied to the present disclosure. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), or a portable computer (e.g., a notebook). The hand-held device may be referred to as a mobile station (MS), a user terminal (UT), a Mobile Subscriber Station (MSS), a Subscriber Station (SS), an Advanced Mobile Station (AMS), or a Wireless Terminal (WT).

Referring to FIG. 28, a hand-held device 100 may include an antenna unit 108, a communication unit 110, a control unit 120, a memory unit 130, a power supply unit 140 a, an interface unit 140 b, and an I/O unit 140 c. The antenna unit 108 may be configured as a part of the communication unit 110. Blocks 110 to 130/140 a to 140 c correspond to the blocks 110 to 130/140 of FIG. 30, respectively.

The communication unit 110 may transmit and receive signals (e.g., data and control signals) to and from other wireless devices or BSs. The control unit 120 may perform various operations by controlling constituent elements of the hand-held device 100. The control unit 120 may include an Application Processor (AP). The memory unit 130 may store data/parameters/programs/code/commands needed to drive the hand-held device 100. The memory unit 130 may store input/output data/information. The power supply unit 140 a may supply power to the hand-held device 100 and include a wired/wireless charging circuit, a battery, etc. The interface unit 140 b may support connection of the hand-held device 100 to other external devices. The interface unit 140 b may include various ports (e.g., an audio I/O port and a video I/O port) for connection with external devices. The I/O unit 140 c may input or output video information/signals, audio information/signals, data, and/or information input by a user. The I/O unit 140 c may include a camera, a microphone, a user input unit, a display unit 140 d, a speaker, and/or a haptic module.

As an example, in the case of data communication, the I/O unit 140 c may acquire information/signals (e.g., touch, text, voice, images, or video) input by a user and the acquired information/signals may be stored in the memory unit 130. The communication unit 110 may convert the information/signals stored in the memory into radio signals and transmit the converted radio signals to other wireless devices directly or to a BS. The communication unit 110 may receive radio signals from other wireless devices or the BS and then restore the received radio signals into original information/signals. The restored information/signals may be stored in the memory unit 130 and may be output as various types (e.g., text, voice, images, video, or haptic) through the I/O unit 140 c.

Examples of Vehicles or Autonomous Vehicles to which the Present Disclosure is Applied

FIG. 29 illustrates a vehicle or an autonomous driving vehicle applied to the present disclosure. The vehicle or autonomous driving vehicle may be implemented by a mobile robot, a car, a train, a manned/unmanned Aerial Vehicle (AV), a ship, etc.

Referring to FIG. 29, a vehicle or autonomous driving vehicle 100 may include an antenna unit 108, a communication unit 110, a control unit 120, a driving unit 140 a, a power supply unit 140 b, a sensor unit 140 c, and an autonomous driving unit 140 d. The antenna unit 108 may be configured as a part of the communication unit 110. The blocks 110/130/140 a to 140 d correspond to the blocks 110/130/140 of FIG. 27, respectively

The communication unit 110 may transmit and receive signals (e.g., data and control signals) to and from external devices such as other vehicles, BSs (e.g., gNBs and road side units), and servers. The control unit 120 may perform various operations by controlling elements of the vehicle or the autonomous driving vehicle 100. The control unit 120 may include an Electronic Control Unit (ECU). Also, the driving unit 140 a may cause the vehicle or the autonomous driving vehicle 100 to drive on a road. The driving unit 140 a may include an engine, a motor, a powertrain, a wheel, a brake, a steering device, etc. The power supply unit 140 b may supply power to the vehicle or the autonomous driving vehicle 100 and include a wired/wireless charging circuit, a battery, etc. The sensor unit 140 c may acquire a vehicle state, ambient environment information, user information, etc. The sensor unit 140 c may include an Inertial Measurement Unit (IMU) sensor, a collision sensor, a wheel sensor, a speed sensor, a slope sensor, a weight sensor, a heading sensor, a position module, a vehicle forward/backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illumination sensor, a pedal position sensor, etc. The autonomous driving unit 140 d may implement technology for maintaining a lane on which a vehicle is driving, technology for automatically adjusting speed, such as adaptive cruise control, technology for autonomously driving along a determined path, technology for driving by automatically setting a path if a destination is set, and the like

For example, the communication unit 110 may receive map data, traffic information data, etc. from an external server. The autonomous driving unit 140 d may generate an autonomous driving path and a driving plan from the acquired data. The control unit 120 may control the driving unit 140 a such that the vehicle or the autonomous driving vehicle 100 may move along the autonomous driving path according to the driving plan (e.g., speed/direction control). In the middle of autonomous driving, the communication unit 110 may aperiodically/periodically acquire recent traffic information data from the external server and acquire surrounding traffic information data from neighboring vehicles. In the middle of autonomous driving, the sensor unit 140 c may obtain a vehicle state and/or surrounding environment information. The autonomous driving unit 140 d may update the autonomous driving path and the driving plan based on the newly acquired data/information. The communication unit 110 may transfer information about a vehicle position, the autonomous driving path, and/or the driving plan to the external server. The external server may predict traffic information data using AI technology, etc., based on the information collected from vehicles or autonomous driving vehicles and provide the predicted traffic information data to the vehicles or the autonomous driving vehicles.

The embodiments described above are those in which components and features of the present disclosure are combined in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, it is also possible to constitute an embodiment of the present disclosure by combining some components and/or features. The order of operations described in the embodiments of the present disclosure may be changed. Some configurations or features of one embodiment may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is obvious that the embodiments may be configured by combining claims that do not have an explicit citation relationship in the claims or may be included as new claims by amendment after filing.

In this document, embodiments of the present disclosure have been mainly described based on a signal transmission/reception relationship between a terminal and a base station. Such a transmission/reception relationship is extended in the same/similar manner to signal transmission/reception between a terminal and a relay or a base station and a relay. A specific operation described as being performed by a base station in this document may be performed by its upper node in some cases. That is, it is obvious that various operations performed for communication with a terminal in a network comprising a plurality of network nodes including a base station may be performed by the base station or network nodes other than the base station. The base station may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the terminal may be replaced with terms such as User Equipment (UE), Mobile Station (MS), Mobile Subscriber Station (MSS).

In a hardware configuration, the embodiments of the present disclosure may be achieved by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

In a firmware or software configuration, a method according to embodiments of the present disclosure may be implemented in the form of a module, a procedure, a function, etc. Software code may be stored in a memory unit and executed by a processor. The memory unit is located at the interior or exterior of the processor and may transmit and receive data to and from the processor via various known means

As described before, a detailed description has been given of preferred embodiments of the present disclosure so that those skilled in the art may implement and perform the present disclosure. While reference has been made above to the preferred embodiments of the present disclosure, those skilled in the art will understand that various modifications and alterations may be made to the present disclosure within the scope of the present disclosure. For example, those skilled in the art may use the components described in the foregoing embodiments in combination. The above embodiments are therefore to be construed in all aspects as illustrative and not restrictive. The scope of the disclosure should be determined by the appended claims and their legal equivalents, not by the above description, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

INDUSTRIAL APPLICABILITY

The above-described embodiments of the present disclosure are applicable to various mobile communication systems. 

1. A method for transmitting a sidelink signal by a user equipment (UE) in a wireless communication system supporting sidelink, the method comprising: measuring status information including mobility information; receiving a first sidelink signal including control information; and determining whether to transmit a second sidelink signal, wherein the UE monitors whether a third sidelink signal from each of other UEs is received during a predetermined period based on the control information having information about a cluster area and the status information having location information belonging to the cluster area, and wherein whether to transmit the second sidelink signal is determined based on the monitoring result.
 2. The method according to claim 1, wherein the second sidelink signal is transmitted when the third sidelink signal is not received during the predetermined period.
 3. The method according to claim 1, wherein when the third sidelink signal is received during the predetermined period and the third sidelink signal includes information on a geographic area corresponding to the cluster area, the transmission of the second sidelink signal is not allowed.
 4. The method according to claim 3, further comprising: receiving at least one of a personal safety message (PSM), a cooperative awareness message (CAM), a decentralized environmental notification message (DENM), and a threat notification message (TNM); and calculating a collision risk (CR) value based on the received at least one message and the status information.
 5. The method according to claim 4, wherein when the third sidelink signal is received during the predetermined period and the calculated collision risk (CR) value is equal to or greater than a collision risk (CR) value obtained from the third sidelink signal, the second sidelink signal is transmitted.
 6. The method according to claim 4, wherein when the control information further includes information for a collision risk (CR) reference value and the calculated collision risk value is equal to or greater than the collision risk reference value, the second sidelink signal is transmitted regardless of reception or non-reception of the third sidelink signal.
 7. The method according to claim 4, wherein when the third sidelink signal is received during the predetermined period, and a collision region and time predicted based on the state information and the at least one message correspond to the collision region and time included in the third sidelink signal, the transmission of the second sidelink signal is not allowed.
 8. The method according to claim 1, wherein when the control information further includes identifier (ID) information for each cluster area and ID information for the cluster area corresponding to the location information included in the status information matches the ID of the UE, the second sidelink signal is transmitted regardless of reception or non-reception of the third sidelink signal.
 9. The method according to claim 1, wherein the control information further includes instruction information indicating any one of schemes for transmitting a plurality of clustering-based sidelink signals.
 10. The method according to claim 9, wherein the second sidelink signal includes at least one of a collision risk (CR) value, a geographical area, a collision area, and a collision time, based on the instruction information.
 11. The method according to claim 1, wherein the second sidelink signal includes a personal safety message (PSM) including collision avoidance guide information that requests change of a movement angle and a movement speed.
 12. The method according to claim 11, wherein the personal safety message (PSM) further includes information about a collision area and a collision time that are estimated by the user equipment (UE).
 13. A user equipment (UE) configured to transmit a safety message in a wireless communication system supporting sidelink, the user equipment (UE) comprising: a radio frequency (RF) transceiver; and a processor connected to the RF transceiver, wherein the processor is configured to measure status information including mobility information, receive a first sidelink signal including control information, monitor whether a third sidelink signal from each of other UEs is received during a predetermined period based on the control information having information about a cluster area and the status information having location information belonging to the cluster area, and determine whether to transmit the second sidelink signal based on the result of monitoring.
 14. A chip set configured to transmit a safety message in a wireless communication system supporting sidelink, the chip set comprising: at least one processor; and at least one memory operatively connected to the at least one processor, and configured to store instructions such that the at least one processor performs specific operations by executing the instructions, wherein the specific operations include: measuring status information including mobility information; receiving a first sidelink signal including control information; monitoring whether a third sidelink signal from each of other UEs is received during a predetermined period based on the control information having information about a cluster area and the status information having location information belonging to the cluster area; and determining whether to transmit the second sidelink signal based on the result of monitoring.
 15. The chip set according to claim 14, wherein: the processor is configured to control a driving mode of a device connected to the chip set, based on the cluster area. 